Rotomolded articles

ABSTRACT

This disclosure relates to rotomolded articles, having a wall structure, where the wall structure contains at least one layer containing an ethylene interpolymer product, or a blend containing an ethylene interpolymer product, where the ethylene interpolymer product has: a Dilution Index (Y d ) greater than −1.0; total catalytic metal ≧3.0 ppm; ≧0.03 terminal vinyl unsaturations per 100 carbon atoms. The ethylene interpolymer products have a melt index from about 0.5 to about 15 dg/minute, a density from about 0.930 to about 0.955 g/cm 3 , a polydispersity (M w /M n ) from about 2 to about 6 and a CDBI 50  from about 50% to about 98%. Further, the ethylene interpolymer products are a blend of at least two ethylene interpolymers; where one ethylene interpolymer is produced with a single-site catalyst formulation and at least one ethylene interpolymer is produced with a heterogeneous catalyst formulation.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application is a continuation-in-part of U.S. application Ser. No.14/918,964, filed on Oct. 21, 2015, entitled “Rotomolded Articles, whichclaims priority to Canadian Patent Application No. CA 2,868,640, filedOct. 21, 2014 and entitled “Solution Polymerization Process” which areherein incorporated by reference in their entirety.

FIELD

This disclosure relates rotomolded articles containing at least oneethylene interpolymer product manufactured in a continuous solutionpolymerization process utilizing at least two reactors employing atleast one single-site catalyst formulation and at least oneheterogeneous catalyst formulation to produce manufactured articleshaving improved ESCR, impact and stiffness.

BACKGROUND

Ethylene interpolymers products are widely used in rotomoldingapplications to produce a wide variety of manufactured articles.Non-limiting examples of rotomolded articles include: toys, bins,containers, helmets, boats, large tanks. Such articles are producedusing rotomolding equipment, non-limiting examples include: clamshellmachines, shuttle machines, swing arm machines, carousel machines andthe like. There is a need to improve the Environmental Stress CrackResistance (ESCR) of rotomolding articles, while maintaining orincreasing the stiffness and impact properties, e.g., ARM Impact at lowtemperature (−40° C.). It is well known to those of ordinary experiencein the art that the stiffness of a rotomolded article can be increasedby increasing the density of the ethylene interpolymer; however, it isalso well known that ESCR typically decreases as density increases.

Herein, ethylene interpolymer products are disclosed that can befabricated into rotomolded parts that have high ESCR, good stiffness andimpact properties relative to comparative ethylene interpolymers. Theethylene interpolymer products disclosed were produced in a solutionpolymerization process, where catalyst components, solvent, monomers andhydrogen are fed under pressure to more than one reactor. For ethylenehomo polymerization, or ethylene copolymerization, solution reactortemperatures can range from about 80° C. to about 300° C. whilepressures generally range from about 3 MPag to about 45 MPag and theethylene interpolymer produced remains dissolved in the solvent. Theresidence time of the solvent in the reactor is relatively short, forexample, from about 1 second to about 20 minutes. The solution processcan be operated under a wide range of process conditions that allow theproduction of a wide variety of ethylene interpolymers. Post reactor,the polymerization reaction is quenched to prevent furtherpolymerization, by adding a catalyst deactivator, and passivated, byadding an acid scavenger. Once passivated, the polymer solution isforwarded to a polymer recovery operation where the ethyleneinterpolymer is separated from process solvent, unreacted residualethylene and unreacted optional α-olefin(s).

SUMMARY OF DISCLOSURE

This Application claims priority to Canadian Patent Application No. CA2,868,640, filed Oct. 21, 2014 and entitled “SOLUTION POLYMERIZATIONPROCESS”. This Application is a continuation in part of U.S. Ser. No.14/918,964 entitled “Rotomolded Articles”.

Embodiment of this disclosure include rotomolded articles having a wallstructure, where the wall structure contains at least one layercontaining an ethylene interpolymer product comprising: (i) a firstethylene interpolymer; (ii) a second ethylene interpolymer, and; (iii)optionally a third ethylene interpolymer; where the ethyleneinterpolymer product has a Dilution Index, Y_(d), greater than −1.0.

Embodiment of this include rotomolded articles having a wall structure,where the wall structure contains at least one layer containing anethylene interpolymer product comprising (i) a first ethyleneinterpolymer; (ii) a second ethylene interpolymer, and; (iii) optionallya third ethylene interpolymer; where the ethylene interpolymer has ≧0.03terminal vinyl unsaturations per 100 carbon atoms.

Embodiment of this disclosure include rotomolded articles having a wallstructure, where the wall structure contains at least one layercontaining an ethylene interpolymer product comprising: (i) a firstethylene interpolymer; (ii) a second ethylene interpolymer, and; (iii)optionally a third ethylene interpolymer; where the ethyleneinterpolymer product has ≧3 parts per million (ppm) of a total catalyticmetal.

Further embodiment include rotomolded articles having a wall structure,where the wall structure contains at least one layer containing anethylene interpolymer product comprising: (i) a first ethyleneinterpolymer; (i) a first ethylene interpolymer; (ii) a second ethyleneinterpolymer, and; (iii) optionally a third ethylene interpolymer; wherethe ethylene interpolymer product has a Dilution Index, Y_(d), greaterthan −1.0 and ≧0.03 terminal vinyl unsaturations per 100 carbon atoms or≧3 parts per million (ppm) of a total catalytic metal.

Additional embodiment include rotomolded articles having a wallstructure, where the wall structure contains at least one layercontaining an ethylene interpolymer product comprising: (i) a firstethylene interpolymer; (ii) a second ethylene interpolymer, and; (iii)optionally a third ethylene interpolymer; where the ethyleneinterpolymer product has ≧0.03 terminal vinyl unsaturations per 100carbon atoms and ≧3 parts per million (ppm) of a total catalytic metal.

The ethylene interpolymer products disclosed here have a melt index fromabout 0.5 to about 15 dg/minute, a density from about 0.930 to about0.955 g/cm³, a M_(w)/M_(n) from about 2 to about 6 and a CDBI₅₀ fromabout 50% to about 98%; where melt index is measured according to ASTMD1238 (2.16 kg load and 190° C.) and density is measured according toASTM D792.

Further, the disclosed ethylene interpolymer products contain: (i) fromabout 15 to about 60 weight percent of a first ethylene interpolymerhaving a melt index from about 0.01 to about 200 dg/minute and a densityfrom about 0.855 g/cm³ to about 0.975 g/cm³; (ii) from about 30 to about85 weight percent of a second ethylene interpolymer having a melt indexfrom about 0.3 to about 1000 dg/minute and a density from about 0.89g/cm³ to about 0.975 g/cm³, and; (iii) optionally from about 0 to about30 weight percent of a third ethylene interpolymer having a melt indexfrom about 0.5 to about 2000 dg/minute and a density from about 0.89 toabout 0.975 g/cm³; where weight percent is the weight of the first,second or third ethylene polymer divided by the weight of ethyleneinterpolymer product.

Embodiments of this disclosure include rotomolded articles comprisingone or more ethylene interpolymer product synthesized in a solutionpolymerization process containing from 0.1 to about 2 mole percent ofone or more α-olefins.

Further, the first ethylene interpolymer is synthesized using asingle-site catalyst formulation and the second ethylene interpolymer issynthesized using a first heterogeneous catalyst formulation.Embodiments of rotomolded articles may contain ethylene interpolymerswhere the third ethylene interpolymer is synthesized using a firstheterogeneous catalyst formulation or a second heterogeneous catalystformulation.

The second ethylene interpolymer may be synthesized using a firstin-line Ziegler Natta catalyst formulation or a first batchZiegler-Natta catalyst formulation; optionally, the third ethyleneinterpolymer is synthesized using the first in-line Ziegler Nattacatalyst formulation or the first batch Ziegler-Natta catalystformulation. The optional third ethylene interpolymer may be synthesizedusing a second in-line Ziegler Natta catalyst formulation or a secondbatch Ziegler-Natta catalyst formulation.

Embodiments of this disclosure include rotomolded articles, containingand ethylene interpolymer product, where the ethylene interpolymerproduct has ≦1 part per million (ppm) of a metal A; where metal Aoriginates from the single-site catalyst formulation; non-limitingexamples of metal A include titanium, zirconium or hafnium.

Further embodiments include rotomolded articles, containing an ethyleneinterpolymer product, where the ethylene interpolymer product has ametal B and optionally a metal C; where the total amount of metal B andmetal C is from about 3 to about 11 parts per million (ppm); where metalB originates from a first heterogeneous catalyst formulation and metal Coriginates form an optional second heterogeneous catalyst formation.Metals B and C are independently selected from the followingnon-limiting examples: titanium, zirconium, hafnium, vanadium, niobium,tantalum, chromium, molybdenum, tungsten, manganese, technetium,rhenium, iron, ruthenium or osmium. Metals B and C may be the samemetal.

Additional embodiments of rotomolded articles contain ethyleneinterpolymer products where the first ethylene interpolymer has a firstM_(w)/M_(n), the second ethylene interpolymer has a second M_(w)/M_(n)and the optional third ethylene has a third M_(w)/M_(n); where the firstM_(w)/M_(n) is lower than the second M_(w)/M_(n) and the optional thirdM_(w)/M_(n). Embodiments also include ethylene interpolymer productswhere the blending of the second ethylene interpolymer and the thirdethylene interpolymer form an ethylene interpolymer blend having afourth M_(w)/M_(n); where the fourth M_(w)/M_(n) is not broader than thesecond M_(w)/M_(n). Additional ethylene interpolymer product embodimentsare characterized as having both the second M_(w)/M_(n) and the thirdM_(w)/M_(n) less than about 4.0.

Further, embodiments of rotomolded articles also include ethyleneinterpolymer products where the first ethylene interpolymer has a firstCDBI₅₀ from about 70 to about 98%, the second ethylene interpolymer hasa second CDBI₅₀ from about 45 to about 98% and the optional thirdethylene interpolymer has a third CDBI₅₀ from about 35 to about 98%.Other embodiments include ethylene interpolymer products where the firstCDBI₅₀ is higher than the second CDBI₅₀; optionally the first CDBI₅₀ ishigher than the third CDBI₅₀.

Embodiments of the rotomolded articles disclosed herein, comprise a wallstructure, where the wall structure comprises at least one layercomprising an ethylene interpolymer product comprising: (a) a firstethylene interpolymer synthesized with a single-site catalystformulation; (b) a second ethylene interpolymer synthesized with a firstheterogeneous catalyst formulation, and; (c) optionally a third ethyleneinterpolymer synthesized with the first heterogeneous catalystformulation or a second heterogeneous catalyst formulation; wherein thewall structure, (i) has an ARM impact mean failure energy of ≧120 ft·lb,(ii) has an ARM impact ductility of ≧50%, and; (iii) passes an ESCR testCondition A100 and a comparative wall structure fails the ESCR testCondition A100, or (iv) passes an ESCR test Condition B100 and acomparative wall structure fails the ESCR test Condition B100, or both(iii) and (iv); where the comparative wall structure has the sameconstruction but the ethylene interpolymer product is replaced with acomparative ethylene interpolymer synthesized using one or moresingle-site catalyst formulations. In this disclosure, ESCR testing wasemployed as a pass/fail test. Specifically, the wall structure of arotomolded part passed ESCR test Condition A100 if the failure time(F^(A) ₅₀) was ≧1000 hr, where F^(A) ₅₀ was estimated graphically asdescribed in Annex A1 of ASTM D1693; in contrast, the wall structurefailed ESCR text Condition A100 if F^(A) ₅₀ was <1000 hr. Similarly, thewall structure of a rotomolded part passed ESCR test Condition B100 ifthe failure time (F^(B) ₅₀) was ≧1000 hr, where F^(B) ₅₀ was estimatedgraphically as described in Annex A1 of ASTM D1693; in contrast, thewall structure failed the ESCR text Condition B100 if F^(B) ₅₀ was <1000hr. In this disclosure the ARM impact mean failure energy and the ARMimpact ductility are measured at −40° C. according to ASTM D5628. In theARM Impact test, a rotomolded part having an ARM Mean Failure Energy≧120 lb·ft in combination with an ARM Ductility 50% was considered agood part. To be more clear, a wall structure having an ARM Mean FailureEnergy 120 lb·ft and an ARM Ductility ≧50% passed the ARM Impact test;in contrast, a wall structure having an ARM Mean Failure Energy <120lb·ft or an ARM Ductility <50% failed the ARM Impact test.

BRIEF DESCRIPTION OF FIGURES

The following Figures are presented for the purpose of illustratingselected embodiments of this disclosure; it being understood, that theembodiments shown do not limit this disclosure.

FIG. 1 plots the Environmental Stress Crack Resistance, ESCR, (hr)versus the flexural 2% secant modulus (MPa).

FIG. 2 is a plot of Dilution Index (Y_(d)) (Y_(d) has dimensions ofdegrees (°)) and Dimensionless Modulus (X_(d)) for:

-   -   Comparative S (open triangle, Y_(d)=X_(d)=0) is an ethylene        interpolymer comprising an ethylene interpolymer synthesized        using an in-line Ziegler-Natta catalyst in a solution process        (rheological reference);    -   Examples 6, 71, 73, 101, 102, 103, 110, 115, 200, 201 (solid        circle, Y_(d)>−1.0 and X_(d)<0) are ethylene interpolymer        products as described in this disclosure comprising a first        ethylene interpolymer synthesized using a single-site catalyst        formulation and a second ethylene interpolymer synthesized using        an in-line Ziegler-Natta catalyst formulation in a solution        process;    -   Examples 120, 130 and 131 (solid square, Y_(d)>0, X_(d)>0) are        ethylene interpolymer products as described in this disclosure;    -   Comparatives D and E (open diamond, Y_(d)<0, X_(d)>0) are        ethylene interpolymers comprising a first ethylene interpolymer        synthesized using a single-site catalyst formation and a second        ethylene interpolymer synthesized using a batch Ziegler-Natta        catalyst formulation in a solution process, and;    -   Comparative A (open square, Y_(d)>−1.0 and X_(d)<0) is an        ethylene interpolymer comprising a first and second ethylene        interpolymer synthesized using a single-site catalyst formation        in a solution process.    -   Comparative Example 41 (open circle, Y_(d)>−1.0 and X_(d)<0) is        an ethylene interpolymer comprising a first and second ethylene        interpolymer synthesized using a single-site catalyst formation        in a solution process.

FIG. 3 illustrates a typical Van Gurp Palmen (VGP) plot of phase angle[°] versus complex modulus [kPa].

FIG. 4 plots the Storage modulus (G′) and loss modulus (G″) showing thecross over frequency cox and the two decade shift in phase angle toreach ω_(c) (ω_(c)=0.01 ω_(x)).

FIG. 5 compares the amount of terminal vinyl unsaturations per 100carbon atoms (terminal vinyl/100 C) in the ethylene interpolymerproducts of this disclosure (solid circles) with Comparatives B, C, E,E2, G, H, H2, I and J (open triangles).

FIG. 6 compares the amount of total catalytic metal (ppm) in theethylene interpolymer products of this disclosure (solid circles) withComparatives B, C, E, E2, G, H, H2, I and J (open triangles).

FIG. 7 illustrates the deconvolution of Example 73; the experimentallymeasured GPC chromatogram was deconvoluted into a first, a second and athird ethylene interpolymer.

FIG. 8 illustrates the deconvolution of Comparative Example 16, i.e. theexperimentally measured GPC chromatogram was deconvoluted into a firstand a second ethylene interpolymer.

DEFINITION OF TERMS

Other than in the examples or where otherwise indicated, all numbers orexpressions referring to quantities of ingredients, extrusionconditions, etc., used in the specification and claims are to beunderstood as modified in all instances by the term “about.”Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that can vary depending upon the desired properties thatthe various embodiments desire to obtain. At the very least, and not asan attempt to limit the application of the doctrine of equivalents tothe scope of the claims, each numerical parameter should at least beconstrued in light of the number of reported significant digits and byapplying ordinary rounding techniques. The numerical values set forth inthe specific examples are reported as precisely as possible. Anynumerical values, however, inherently contain certain errors necessarilyresulting from the standard deviation found in their respective testingmeasurements.

It should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between andincluding the recited minimum value of 1 and the recited maximum valueof 10; that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10. Because the disclosednumerical ranges are continuous, they include every value between theminimum and maximum values. Unless expressly indicated otherwise, thevarious numerical ranges specified in this application areapproximations.

All compositional ranges expressed herein are limited in total to and donot exceed 100 percent (volume percent or weight percent) in practice.Where multiple components can be present in a composition, the sum ofthe maximum amounts of each component can exceed 100 percent, with theunderstanding that, and as those skilled in the art readily understand,that the amounts of the components actually used will conform to themaximum of 100 percent.

In order to form a more complete understanding of this disclosure thefollowing terms are defined and should be used with the accompanyingfigures and the description of the various embodiments throughout.

The term “Dilution Index (Y_(d))” and “Dimensionless Modulus (Xd)” arebased on rheological measurements and are fully described in thisdisclosure.

As used herein, the term “monomer” refers to a small molecule that maychemically react and become chemically bonded with itself or othermonomers to form a polymer.

As used herein, the term “α-olefin” is used to describe a monomer havinga linear hydrocarbon chain containing from 3 to 20 carbon atoms having adouble bond at one end of the chain.

As used herein, the term “ethylene polymer”, refers to macromoleculesproduced from ethylene monomers and optionally one or more additionalmonomers; regardless of the specific catalyst or specific process usedto make the ethylene polymer. In the polyethylene art, the one or moreadditional monomers are called “comonomer(s)” and often includeα-olefins. The term “homopolymer” refers to a polymer that contains onlyone type of monomer. Common ethylene polymers include high densitypolyethylene (HDPE), medium density polyethylene (MDPE), linear lowdensity polyethylene (LLDPE), very low density polyethylene (VLDPE),ultralow density polyethylene (ULDPE), plastomer and elastomers. Theterm ethylene polymer also includes polymers produced in a high pressurepolymerization processes; non-limiting examples include low densitypolyethylene (LDPE), ethylene vinyl acetate copolymers (EVA), ethylenealkyl acrylate copolymers, ethylene acrylic acid copolymers and metalsalts of ethylene acrylic acid (commonly referred to as ionomers). Theterm ethylene polymer also includes block copolymers which may include 2to 4 comonomers. The term ethylene polymer also includes combinationsof, or blends of, the ethylene polymers described above.

The term “ethylene interpolymer” refers to a subset of polymers withinthe “ethylene polymer” group that excludes polymers produced in highpressure polymerization processes; non-limiting examples of polymersproduced in high pressure processes include LDPE and EVA (the latter isa copolymer of ethylene and vinyl acetate).

The term “heterogeneous ethylene interpolymers” refers to a subset ofpolymers in the ethylene interpolymer group that are produced using aheterogeneous catalyst formulation; non-limiting examples of whichinclude Ziegler-Natta or chromium catalysts.

The term “homogeneous ethylene interpolymer” refers to a subset ofpolymers in the ethylene interpolymer group that are produced usingmetallocene or single-site catalysts. Typically, homogeneous ethyleneinterpolymers have narrow molecular weight distributions, for examplegel permeation chromatography (GPC) M_(w)/M_(n) values of less than 2.8;M_(w) and M_(n) refer to weight and number average molecular weights,respectively. In contrast, the M_(w)/M_(n) of heterogeneous ethyleneinterpolymers are typically greater than the M_(w)/M_(n) of homogeneousethylene interpolymers. In general, homogeneous ethylene interpolymersalso have a narrow comonomer distribution, i.e. each macromoleculewithin the molecular weight distribution has a similar comonomercontent. Frequently, the composition distribution breadth index “CDBI”is used to quantify how the comonomer is distributed within an ethyleneinterpolymer, as well as to differentiate ethylene interpolymersproduced with different catalysts or processes. The “CDBI₅₀” is definedas the percent of ethylene interpolymer whose composition is within 50%of the median comonomer composition; this definition is consistent withthat described in U.S. Pat. No. 5,206,075 assigned to Exxon ChemicalPatents Inc. The CDBI₅₀ of an ethylene interpolymer can be calculatedfrom TREF curves (Temperature Rising Elution Fractionation); the TREFmethod is described in Wild, et al., J. Polym. Sci., Part B, Polym.Phys., Vol. 20 (3), pages 441-455. Typically the CDBI₅₀ of homogeneousethylene interpolymers are greater than about 70%. In contrast, theCDBI₅₀ of α-olefin containing heterogeneous ethylene interpolymers aregenerally lower than the CDBI₅₀ of homogeneous ethylene interpolymers.

It is well known to those skilled in the art, that homogeneous ethyleneinterpolymers are frequently further subdivided into “linear homogeneousethylene interpolymers” and “substantially linear homogeneous ethyleneinterpolymers”. These two subgroups differ in the amount of long chainbranching: more specifically, linear homogeneous ethylene interpolymershave less than about 0.01 long chain branches per 1000 carbon atoms;while substantially linear ethylene interpolymers have greater thanabout 0.01 to about 3.0 long chain branches per 1000 carbon atoms. Along chain branch is macromolecular in nature, i.e. similar in length tothe macromolecule that the long chain branch is attached to. Hereafter,in this disclosure, the term “homogeneous ethylene interpolymer” refersto both linear homogeneous ethylene interpolymers and substantiallylinear homogeneous ethylene interpolymers.

Herein, the term “polyolefin” includes ethylene polymers and propylenepolymers; non-limiting examples of propylene polymers include isotactic,syndiotactic and atactic propylene homopolymers, random propylenecopolymers containing at least one comonomer and impact polypropylenecopolymers or heterophasic polypropylene copolymers.

The term “thermoplastic” refers to a polymer that becomes liquid whenheated, will flow under pressure and solidify when cooled. Thermoplasticpolymers include ethylene polymers as well as other polymers commonlyused in the plastic industry; non-limiting examples of other polymerscommonly used include barrier resins (EVOH), tie resins, polyethyleneterephthalate (PET), polyamides and the like.

As used herein the term “monolayer” refers a rotomolded article wherethe wall structure comprises a single layer.

As used herein, the terms “hydrocarbyl”, “hydrocarbyl radical” or“hydrocarbyl group” refers to linear or cyclic, aliphatic, olefinic,acetylenic and aryl (aromatic) radicals comprising hydrogen and carbonthat are deficient by one hydrogen.

As used herein, an “alkyl radical” includes linear, branched and cyclicparaffin radicals that are deficient by one hydrogen radical;non-limiting examples include methyl (—CH₃) and ethyl (—CH₂CH₃)radicals. The term “alkenyl radical” refers to linear, branched andcyclic hydrocarbons containing at least one carbon-carbon double bondthat is deficient by one hydrogen radical.

Herein the term “R1” and its superscript form “^(R1)” refers to a firstreactor in a continuous solution polymerization process; it beingunderstood that R1 is distinctly different from the symbol R¹; thelatter is used in chemical formula, e.g. representing a hydrocarbylgroup. Similarly, the term “R2” and it's superscript form “^(R2)” refersto a second reactor, and; the term “R3” and it's superscript form“^(R3)” refers to a third reactor.

DETAILED DESCRIPTION

Catalysts

Organometallic catalyst formulations that are efficient in polymerizingolefins are well known in the art. In the embodiments disclosed herein,at least two catalyst formulations are employed in a continuous solutionpolymerization process. One of the catalyst formulations is asingle-site catalyst formulation that produces a first ethyleneinterpolymer. The other catalyst formulation is a heterogeneous catalystformulation that produces a second ethylene interpolymer. Optionally athird ethylene interpolymer is produced using the heterogeneous catalystformulation that was used to produce the second ethylene interpolymer,or a different heterogeneous catalyst formulation may be used to producethe third ethylene interpolymer. In the continuous solution process, theat least one homogeneous ethylene interpolymer and the at least oneheterogeneous ethylene interpolymer are solution blended and an ethyleneinterpolymer product is produced.

Single Site Catalyst Formulation

The catalyst components which make up the single site catalystformulation are not particularly limited, i.e. a wide variety ofcatalyst components can be used. One non-limiting embodiment of a singlesite catalyst formulation comprises the following three or fourcomponents: a bulky ligand-metal complex; an alumoxane co-catalyst; anionic activator and optionally a hindered phenol. In Table 2A of thisdisclosure: “(i)” refers to the amount of “component (i)”, i.e. thebulky ligand-metal complex added to R1; “(ii)” refers to “component(ii)”, i.e. the alumoxane co-catalyst; “(iii)” refers to “component(iii)” i.e. the ionic activator, and; “(iv)” refers to “component (iv)”,i.e. the optional hindered phenol.

Non-limiting examples of component (i) are represented by formula (I):(L^(A))_(a)M(PI)_(b)(Q)_(n)  (I)

wherein (L^(A)) represents a bulky ligand; M represents a metal atom; PIrepresents a phosphinimine ligand; Q represents a leaving group; a is 0or 1; b is 1 or 2; (a+b)=2; n is 1 or 2, and; the sum of (a+b+n) equalsthe valance of the metal M.

Non-limiting examples of the bulky ligand L^(A) in formula (I) includeunsubstituted or substituted cyclopentadienyl ligands orcyclopentadienyl-type ligands, heteroatom substituted and/or heteroatomcontaining cyclopentadienyl-type ligands. Additional non-limitingexamples include, cyclopentaphen-anthreneyl ligands, unsubstituted orsubstituted indenyl ligands, benzindenyl ligands, unsubstituted orsubstituted fluorenyl ligands, octahydrofluorenyl ligands,cyclooctatetraendiyl ligands, cyclopentacyclododecene ligands, azenylligands, azulene ligands, pentalene ligands, phosphoyl ligands,phosphinimine, pyrrolyl ligands, pyrozolyl ligands, carbazolyl ligands,borabenzene ligands and the like, including hydrogenated versionsthereof, for example tetrahydroindenyl ligands. In other embodiments,L^(A) may be any other ligand structure capable of η-bonding to themetal M, such embodiments include both η³-bonding and η⁵-bonding to themetal M. In other embodiments, L^(A) may comprise one or moreheteroatoms, for example, nitrogen, silicon, boron, germanium, sulfurand phosphorous, in combination with carbon atoms to form an open,acyclic, or a fused ring, or ring system, for example, aheterocyclopentadienyl ancillary ligand. Other non-limiting embodimentsfor L^(A) include bulky amides, phosphides, alkoxides, aryloxides,imides, carbolides, borollides, porphyrins, phthalocyanines, corrins andother polyazomacrocycles.

Non-limiting examples of metal M in formula (I) include Group 4 metals,titanium, zirconium and hafnium.

The phosphinimine ligand, PI, is defined by formula (II):(R^(p))₃P═N—  (II)

wherein the R^(p) groups are independently selected from: a hydrogenatom; a halogen atom; C₁₋₂₀ hydrocarbyl radicals which are unsubstitutedor substituted with one or more halogen atom(s); a C₁₋₈ alkoxy radical;a C₆₋₁₀ aryl radical; a C₆₋₁₀ aryloxy radical; an amido radical; a silylradical of formula —Si(R^(s))₃, wherein the R^(s) groups areindependently selected from, a hydrogen atom, a C₁₋₈ alkyl or alkoxyradical, a C₆₋₁₀ aryl radical, a C₆₋₁₀ aryloxy radical, or a germanylradical of formula —Ge(R^(G))₃, wherein the R^(G) groups are defined asR^(s) is defined in this paragraph.

The leaving group Q is any ligand that can be abstracted from formula(I) forming a catalyst species capable of polymerizing one or moreolefin(s). An equivalent term for Q is an “activatable ligand”, i.e.equivalent to the term “leaving group”. In some embodiments, Q is amonoanionic labile ligand having a sigma bond to M. Depending on theoxidation state of the metal, the value for n is 1 or 2 such thatformula (I) represents a neutral bulky ligand-metal complex.Non-limiting examples of Q ligands include a hydrogen atom, halogens,C₁₋₂₀ hydrocarbyl radicals, C₁₋₂₀ alkoxy radicals, C₅₋₁₀ aryl oxideradicals; these radicals may be linear, branched or cyclic or furthersubstituted by halogen atoms, C₁₋₁₀ alkyl radicals, C₁₋₁₀ alkoxyradicals, C₆₋₁₀ arly or aryloxy radicals. Further non-limiting examplesof Q ligands include weak bases such as amines, phosphines, ethers,carboxylates, dienes, hydrocarbyl radicals having from 1 to 20 carbonatoms. In another embodiment, two Q ligands may form part of a fusedring or ring system.

Further embodiments of component (i) of the single site catalystformulation include structural, optical or enantiomeric isomers (mesoand racemic isomers) and mixtures thereof of the bulky ligand-metalcomplexes described in formula (I) above.

The second single site catalyst component, component (ii), is analumoxane co-catalyst that activates component (i) to a cationiccomplex. An equivalent term for “alumoxane” is “aluminoxane”; althoughthe exact structure of this co-catalyst is uncertain, subject matterexperts generally agree that it is an oligomeric species that containrepeating units of the general formula (III):(R)₂AlO—(Al(R)—O)_(n)—Al(R)₂  (III)

where the R groups may be the same or different linear, branched orcyclic hydrocarbyl radicals containing 1 to 20 carbon atoms and n isfrom 0 to about 50. A non-limiting example of an alumoxane is methylaluminoxane (or MAO) wherein each R group in formula (III) is a methylradical.

The third catalyst component (iii) of the single site catalyst formationis an ionic activator. In general, ionic activators are comprised of acation and a bulky anion; wherein the latter is substantiallynon-coordinating. Non-limiting examples of ionic activators are boronionic activators that are four coordinate with four ligands bonded tothe boron atom. Non-limiting examples of boron ionic activators includethe following formulas (IV) and (V) shown below;[R⁵]⁺[B(R⁷)₄]⁻  (IV)

where B represents a boron atom, R⁵ is an aromatic hydrocarbyl (e.g.triphenyl methyl cation) and each R⁷ is independently selected fromphenyl radicals which are unsubstituted or substituted with from 3 to 5substituents selected from fluorine atoms, C₁₋₄ alkyl or alkoxy radicalswhich are unsubstituted or substituted by fluorine atoms; and a silylradical of formula —Si(R⁹)₃, where each R⁹ is independently selectedfrom hydrogen atoms and C₁₋₄ alkyl radicals, and; compounds of formula(V);[(R⁸)_(t)ZH]⁺[B(R⁷)₄]⁻  (V)

where B is a boron atom, H is a hydrogen atom, Z is a nitrogen orphosphorus atom, t is 2 or 3 and R⁸ is selected from C₁₋₈ alkylradicals, phenyl radicals which are unsubstituted or substituted by upto three C₁₋₄ alkyl radicals, or one R⁸ taken together with the nitrogenatom may form an anilinium radical and R⁷ is as defined above in formula(IV).

In both formula (IV) and (V), a non-limiting example of R⁷ is apentafluorophenyl radical. In general, boron ionic activators may bedescribed as salts of tetra(perfluorophenyl) boron; non-limitingexamples include anilinium, carbonium, oxonium, phosphonium andsulfonium salts of tetra(perfluorophenyl)-boron with anilinium andtrityl (or triphenylmethylium). Additional non-limiting examples ofionic activators include: triethylammonium tetra(phenyl)boron,tripropylammonium tetra(phenyl)boron, tri(n-butyl)ammoniumtetra(phenyl)boron, trimethylammonium tetra(p-tolyl)boron,trimethylammonium tetra(o-tolyl)boron, tributylammoniumtetra(pentafluorophenyl)boron, tripropylammoniumtetra(o,p-dimethylphenyl)boron, tributylammoniumtetra(m,m-dimethylphenyl)boron, tributylammoniumtetra(p-trifluoromethylphenyl)boron, tributylammoniumtetra(pentafluorophenyl)boron, tri(n-butyl)ammonium tetra(o-tolyl)boron,N,N-dimethylanilinium tetra(phenyl)boron, N,N-diethylaniliniumtetra(phenyl)boron, N,N-diethylanilinium tetra(phenyl)n-butylboron,N,N-2,4,6-pentamethylanilinium tetra(phenyl)boron,di-(isopropyl)ammonium tetra(pentafluorophenyl)boron,dicyclohexylammonium tetra(phenyl)boron, triphenylphosphoniumtetra(phenyl)boron, tri(methylphenyl)phosphonium tetra(phenyl)boron,tri(dimethylphenyl)phosphonium tetra(phenyl)boron, tropilliumtetrakispentafluorophenyl borate, triphenylmethyliumtetrakispentafluorophenyl borate,benzene(diazonium)tetrakispentafluorophenyl borate, tropilliumtetrakis(2,3,5,6-tetrafluorophenyl)borate, triphenylmethyliumtetrakis(2,3,5,6-tetrafluorophenyl)borate, benzene(diazonium)tetrakis(3,4,5-trifluorophenyl)borate, tropilliumtetrakis(3,4,5-trifluorophenyl)borate, benzene(diazonium)tetrakis(3,4,5-trifluorophenyl)borate, tropilliumtetrakis(1,2,2-trifluoroethenyl)borate, triphenylmethyliumtetrakis(1,2,2-trifluoroethenyl)borate, benzene(diazonium)tetrakis(1,2,2-trifluoroethenyl)borate, tropilliumtetrakis(2,3,4,5-tetrafluorophenyl)borate, triphenylmethyliumtetrakis(2,3,4,5-tetrafluorophenyl)borate, and benzene(diazonium)tetrakis(2,3,4,5 tetrafluorophenyl)borate. Readily available commercialionic activators include N,N-dimethylanilinium tetrakispentafluorophenylborate, and triphenylmethylium tetrakispentafluorophenyl borate.

The optional fourth catalyst component of the single site catalystformation is a hindered phenol, component (iv). Non-limiting example ofhindered phenols include butylated phenolic antioxidants, butylatedhydroxytoluene, 2,4-di-tertiarybutyl-6-ethyl phenol, 4,4′-methylenebis(2,6-di-tertiary-butylphenol), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene andoctadecyl-3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate.

To produce an active single site catalyst formulation the quantity andmole ratios of the three or four components, (i) through (iv) areoptimized as described below.

Heterogeneous Catalyst Formulations

A number of heterogeneous catalyst formulations are well known to thoseskilled in the art, including, as non-limiting examples, Ziegler-Nattaand chromium catalyst formulations.

In this disclosure, embodiments include an in-line and batchZiegler-Natta catalyst formulations. The term “in-line Ziegler-Nattacatalyst formulation” refers to the continuous synthesis of a smallquantity of active Ziegler-Natta catalyst and immediately injecting thiscatalyst into at least one continuously operating reactor, where thecatalyst polymerizes ethylene and one or more optional α-olefins to forman ethylene interpolymer. The terms “batch Ziegler-Natta catalystformulation” or “batch Ziegler-Natta procatalyst” refer to the synthesisof a much larger quantity of catalyst or procatalyst in one or moremixing vessels that are external to, or isolated from, the continuouslyoperating solution polymerization process. Once prepared, the batchZiegler-Natta catalyst formulation, or batch Ziegler-Natta procatalyst,is transferred to a catalyst storage tank. The term “procatalyst” refersto an inactive catalyst formulation (inactive with respect to ethylenepolymerization); the procatalyst is converted into an active catalyst byadding an alkyl aluminum co-catalyst. As needed, the procatalyst ispumped from the storage tank to at least one continuously operatingreactor, where an active catalyst is formed and polymerizes ethylene andone or more optional α-olefins to form an ethylene interpolymer. Theprocatalyst may be converted into an active catalyst in the reactor orexternal to the reactor.

A wide variety of chemical compounds can be used to synthesize an activeZiegler-Natta catalyst formulation. The following describes variouschemical compounds that may be combined to produce an activeZiegler-Natta catalyst formulation. Those skilled in the art willunderstand that the embodiments in this disclosure are not limited tothe specific chemical compound disclosed.

An active Ziegler-Natta catalyst formulation may be formed from: amagnesium compound, a chloride compound, a metal compound, an alkylaluminum co-catalyst and an aluminum alkyl. In Table 2A of thisdisclosure: “(v)” refers to “component (v)” the magnesium compound; theterm “(vi)” refers to the “component (vi)” the chloride compound;“(vii)” refers to “component (vii)” the metal compound; “(viii)” refersto “component (viii)” alkyl aluminum co-catalyst, and; “(ix)” refers to“component (ix)” the aluminum alkyl. As will be appreciated by thoseskilled in the art, Ziegler-Natta catalyst formulations may containadditional components; a non-limiting example of an additional componentis an electron donor, e.g. amines or ethers.

A non-limiting example of an active in-line Ziegler-Natta catalystformulation can be prepared as follows. In the first step, a solution ofa magnesium compound (component (v)) is reacted with a solution of thechloride compound (component (vi)) to form a magnesium chloride supportsuspended in solution. Non-limiting examples of magnesium compoundsinclude Mg(R¹)₂; wherein the R¹ groups may be the same or different,linear, branched or cyclic hydrocarbyl radicals containing 1 to 10carbon atoms. Non-limiting examples of chloride compounds include R²Cl;wherein R² represents a hydrogen atom, or a linear, branched or cyclichydrocarbyl radical containing 1 to 10 carbon atoms. In the first step,the solution of magnesium compound may also contain an aluminum alkyl(component (ix)). Non-limiting examples of aluminum alkyl includeAl(R³)₃, wherein the R³ groups may be the same or different, linear,branched or cyclic hydrocarbyl radicals containing from 1 to 10 carbonatoms. In the second step a solution of the metal compound (component(vii)) is added to the solution of magnesium chloride and the metalcompound is supported on the magnesium chloride. Non-limiting examplesof suitable metal compounds include M(X)_(n) or MO(X)_(n); where Mrepresents a metal selected from Group 4 through Group 8 of the PeriodicTable, or mixtures of metals selected from Group 4 through Group 8; Orepresents oxygen, and; X represents chloride or bromide; n is aninteger from 3 to 6 that satisfies the oxidation state of the metal.Additional non-limiting examples of suitable metal compounds includeGroup 4 to Group 8 metal alkyls, metal alkoxides (which may be preparedby reacting a metal alkyl with an alcohol) and mixed-ligand metalcompounds that contain a mixture of halide, alkyl and alkoxide ligands.In the third step a solution of an alkyl aluminum co-catalyst (component(viii)) is added to the metal compound supported on the magnesiumchloride. A wide variety of alkyl aluminum co-catalysts are suitable, asexpressed by formula (VI):Al(R⁴)_(p)(OR⁵)_(q)(X)_(r)  (VI)

wherein the R⁴ groups may be the same or different, hydrocarbyl groupshaving from 1 to 10 carbon atoms; the OR⁵ groups may be the same ordifferent, alkoxy or aryloxy groups wherein R⁵ is a hydrocarbyl grouphaving from 1 to 10 carbon atoms bonded to oxygen; X is chloride orbromide, and; (p+q+r)=3, with the proviso that p is greater than 0.Non-limiting examples of commonly used alkyl aluminum co-catalystsinclude trimethyl aluminum, triethyl aluminum, tributyl aluminum,dimethyl aluminum methoxide, diethyl aluminum ethoxide, dibutyl aluminumbutoxide, dimethyl aluminum chloride or bromide, diethyl aluminumchloride or bromide, dibutyl aluminum chloride or bromide and ethylaluminum dichloride or dibromide.

The process described in the paragraph above, to synthesize an activein-line Ziegler-Natta catalyst formulation, can be carried out in avariety of solvents; non-limiting examples of solvents include linear orbranched C₅ to C₁₂ alkanes or mixtures thereof. To produce an activein-line Ziegler-Natta catalyst formulation the quantity and mole ratiosof the five components, (v) through (ix), are optimized as describedbelow.

Additional embodiments of heterogeneous catalyst formulations includeformulations where the “metal compound” is a chromium compound;non-limiting examples include silyl chromate, chromium oxide andchromocene. In some embodiments, the chromium compound is supported on ametal oxide such as silica or alumina. Heterogeneous catalystformulations containing chromium may also include co-catalysts;non-limiting examples of co-catalysts include trialkylaluminum,alkylaluminoxane and dialkoxyalkylaluminum compounds and the like.

Solution Polymerization Process: In-Line Heterogeneous CatalystFormulation

The ethylene interpolymer products disclosed herein, useful in themanufacture of rotomolded parts, were produced in a continuous solutionpolymerization process. This solution process has been fully describedin Canadian Patent Application No. CA 2,868,640, filed Oct. 21, 2014 andentitled “SOLUTION POLYMERIZATION PROCESS”; which is incorporated byreference into this application in its entirety.

Embodiments of this process includes at least two continuously stirredreactors, R1 and R2 and an optional tubular reactor R3. Feeds (solvent,ethylene, at least two catalyst formulations, optional hydrogen andoptional α-olefin) are feed to at least two reactor continuously. Asingle site catalyst formulation is injected into R1 and a firstheterogeneous catalyst formation is injected into R2 and optionally R3.Optionally, a second heterogeneous catalyst formulation is injected intoR3. The single site catalyst formulation includes an ionic activator(component (iii)), a bulky ligand-metal complex (component (i)), analumoxane co-catalyst (component (ii)) and an optional hindered phenol(component (iv)), respectively.

R1 and R2 may be operated in series or parallel modes of operation. Tobe more clear, in series mode 100% of the effluent from R1 flowsdirectly into R2. In parallel mode, R1 and R2 operate independently andthe effluents from R1 and R2 are combined downstream of the reactors.

A heterogeneous catalyst formulation is injected into R2. In oneembodiment a first in-line Ziegler-Natta catalyst formulation isinjected into R2. A first in-line Ziegler-Natta catalyst formation isformed within a first heterogeneous catalyst assembly by optimizing thefollowing molar ratios: (aluminum alkyl)/(magnesium compound) or(ix)/(v); (chloride compound)/(magnesium compound) or (vi)/(v); (alkylaluminum co-catalyst)/(metal compound) or (viii)/(vii), and; (aluminumalkyl)/(metal compound) or (ix)/(vii); as well as the time thesecompounds have to react and equilibrate. Within the first heterogeneouscatalyst assembly the time between the addition of the chloride compoundand the addition of the metal compound (component (vii)) is controlled;hereafter HUT-1 (the first Hold-Up-Time). The time between the additionof component (vii) and the addition of the alkyl aluminum co-catalyst,component (viii), is also controlled; hereafter HUT-2 (the secondHold-Up-Time). In addition, the time between the addition of the alkylaluminum co-catalyst and the injection of the in-line Ziegler-Nattacatalyst formulation into R2 is controlled; hereafter HUT-3 (the thirdHold-Up-Time). Optionally, 100% the alkyl aluminum co-catalyst, may beinjected directly into R2. Optionally, a portion of the alkyl aluminumco-catalyst may be injected into the first heterogeneous catalystassembly and the remaining portion injected directly into R2. Thequantity of in-line heterogeneous catalyst formulation added to R2 isexpressed as the parts-per-million (ppm) of metal compound (component(vii)) in the reactor solution, hereafter “R2 (vii) (ppm)”. Injection ofthe in-line heterogeneous catalyst formulation into R2 produces a secondethylene interpolymer in a second exit stream (exiting R2). Optionallythe second exit stream is deactivated by adding a catalyst deactivator.If the second exit stream is not deactivated the second exit streamenters reactor R3. One embodiment of a suitable R3 design is a tubularreactor. Optionally, one or more of the following fresh feeds may beinjected into R3; solvent, ethylene, hydrogen, α-olefin and a first orsecond heterogeneous catalyst formulation; the latter is supplied from asecond heterogeneous catalyst assembly. The chemical composition of thefirst and second heterogeneous catalyst formulations may be the same, ordifferent, i.e. the catalyst components ((v) through (ix)), mole ratiosand hold-up-times may differ in the first and second heterogeneouscatalyst assemblies. The second heterogeneous catalyst assemblygenerates an efficient catalyst by optimizing hold-up-times and themolar ratios of the catalyst components.

In reactor R3, a third ethylene interpolymer may, or may not, form. Athird ethylene interpolymer will not form if a catalyst deactivator isadded upstream of reactor R3. A third ethylene interpolymer will beformed if a catalyst deactivator is added downstream of R3. The optionalthird ethylene interpolymer may be formed using a variety of operationalmodes (with the proviso that catalyst deactivator is not addedupstream). Non-limiting examples of operational modes include: (a)residual ethylene, residual optional α-olefin and residual activecatalyst entering R3 react to form the third ethylene interpolymer, or;(b) fresh process solvent, fresh ethylene and optionally fresh α-olefinare added to R3 and the residual active catalyst entering R3 forms thethird ethylene interpolymer, or; (c) a second in-line heterogeneouscatalyst formulation is added to R3 to polymerize residual ethylene andresidual optional α-olefin to form the third ethylene interpolymer, or;(d) fresh process solvent, ethylene, optional α-olefin and a secondin-line heterogeneous catalyst formulation are added to R3 to form thethird ethylene interpolymer.

In series mode, R3 produces a third exit stream (the stream exiting R3)containing the first ethylene interpolymer, the second ethyleneinterpolymer and optionally a third ethylene interpolymer. A catalystdeactivator may be added to the third exit stream producing adeactivated solution; with the proviso a catalyst deactivator is notadded if a catalyst deactivator was added upstream of R3.

The deactivated solution passes through a pressure let down device, aheat exchanger and a passivator is added forming a passivated solution.The passivated solution passes through a series of vapor liquidseparators and ultimately the ethylene interpolymer product enterspolymer recover. Non-limiting examples of polymer recovery operationsinclude one or more gear pump, single screw extruder or twin screwextruder that forces the molten ethylene interpolymer product through apelletizer.

Embodiments of the manufactured articles disclosed herein, may also beformed from ethylene interpolymer products synthesized using a batchZiegler-Natta catalyst. Typically, a first batch Ziegler-Nattaprocatalyst is injected into R2 and the procatalyst is activated withinR2 by injecting an alkyl aluminum co-catalyst forming a first batchZiegler-Natta catalyst. Optionally, a second batch Ziegler-Nattaprocatalyst is injected into R3.

Additional Solution Polymerization Process Parameters

A variety of solvents may be used as the process solvent; non-limitingexamples include linear, branched or cyclic C₅ to C₁₂ alkanes.Non-limiting examples of α-olefins include C₃ to C₁₀ α-olefins. It iswell known to individuals of ordinary experience in the art that reactorfeed streams (solvent, monomer, α-olefin, hydrogen, catalyst formulationetc.) must be essentially free of catalyst deactivating poisons;non-limiting examples of poisons include trace amounts of oxygenatessuch as water, fatty acids, alcohols, ketones and aldehydes. Suchpoisons are removed from reactor feed streams using standardpurification practices; non-limiting examples include molecular sievebeds, alumina beds and oxygen removal catalysts for the purification ofsolvents, ethylene and α-olefins, etc.

In operating the continuous solution polymerization process total amountof ethylene supplied to the process can be portioned or split betweenthe three reactors R1, R2 and R3. This operational variable is referredto as the Ethylene Split (ES), i.e., “ES^(R1)”, “ES^(R2)” and “ES^(R3)”refer to the weight percent of ethylene injected in R1, R2 and R3,respectively; with the proviso that ES^(R1)+ES^(R2)+ES^(R3)=100%. Theethylene concentration in each reactor is also controlled. The R1ethylene concentration is defined as the weight of ethylene in reactor 1divided by the total weight of everything added to reactor 1; the R2ethylene concentration (wt %) and R3 ethylene concentration (wt %) aredefined similarly. The total amount of ethylene converted in eachreactor is monitored. The term “Q^(R1)” refers to the percent of theethylene added to R1 that is converted into an ethylene interpolymer bythe catalyst formulation. Similarly Q^(R2) and Q^(R3) represent thepercent of the ethylene added to R2 and R3 that was converted intoethylene interpolymer, in the respective reactor. The term “Q^(T)”represents the total or overall ethylene conversion across the entirecontinuous solution polymerization plant; i.e., Q^(T)=100×[weight ofethylene in the interpolymer product]/([weight of ethylene in theinterpolymer product]+[weight of unreacted ethylene]). Optionally,α-olefin may be added to the continuous solution polymerization process.If added, α-olefin may be proportioned or split between R1, R2 and R3.This operational variable is referred to as the Comonomer Split (CS),i.e. “CS^(R1)”, “CS^(R2)” and “CS^(R3)” refer to the weight percent ofα-olefin comonomer that is injected in R1, R2 and R3, respectively; withthe proviso that CS^(R1)+CS^(R2)+CS^(R3)=100%.

In the continuous polymerization processes described, polymerization isterminated by adding a catalyst deactivator. The catalyst deactivatorsubstantially stops the polymerization reaction by changing activecatalyst species to inactive forms. Suitable deactivators are well knownin the art, non-limiting examples include: amines (e.g., U.S. Pat. No.4,803,259 to Zboril et al.); alkali or alkaline earth metal salts ofcarboxylic acid (e.g., U.S. Pat. No. 4,105,609 to Machan et al.); water(e.g., U.S. Pat. No. 4,731,438 to Bernier et al.); hydrotalcites,alcohols and carboxylic acids (e.g., U.S. Pat. No. 4,379,882 to Miyata);or a combination thereof (U.S. Pat. No. 6,180,730 to Sibtain et al.).

Prior to entering the vapor/liquid separator, a passivator or acidscavenger is added to deactivated solution. Suitable passivators arewell known in the art, non-limiting examples include alkali or alkalineearth metal salts of carboxylic acids or hydrotalcites.

In this disclosure, the number of solution reactors is not particularlyimportant; with the proviso that the continuous solution polymerizationprocess comprises at least two reactors that employ at least onesingle-site catalyst formulation and at least one heterogeneous catalystformulation.

First Ethylene Interpolymer

The first ethylene interpolymer is produced with a single-site catalystformulation. If the optional α-olefin is not added to reactor 1 (R1),then the ethylene interpolymer produced in R1 is an ethylenehomopolymer. If an α-olefin is added, the following weight ratio is oneparameter to control the density of the first ethylene interpolymer:((α-olefin)/(ethylene))^(R1). The symbol “σ¹” refers to the density ofthe first ethylene interpolymer produced in R1. The upper limit on σ¹may be about 0.975 g/cm³; in some cases about 0.965 g/cm³ and; in othercases about 0.955 g/cm³. The lower limit on σ¹ may be about 0.855 g/cm³,in some cases about 0.865 g/cm³, and; in other cases about 0.875 g/cm³.

Methods to determine the CDBI₅₀ (Composition Distribution BranchingIndex) of an ethylene interpolymer are well known to those skilled inthe art. The CDBI₅₀, expressed as a percent, is defined as the percentof the ethylene interpolymer whose comonomer composition is within 50%of the median comonomer composition. It is also well known to thoseskilled in the art that the CDBI₅₀ of ethylene interpolymers producedwith single-site catalyst formulations are higher relative to the CDBI₅₀of α-olefin containing ethylene interpolymers produced withheterogeneous catalyst formulations. The upper limit on the CDBI₅₀ ofthe first ethylene interpolymer (produced with a single-site catalystformulation) may be about 98%, in other cases about 95% and in stillother cases about 90%. The lower limit on the CDBI₅₀ of the firstethylene interpolymer may be about 70%, in other cases about 75% and instill other cases about 80%.

As is well known to those skilled in the art, the M_(w)/M_(n) ofethylene interpolymers produced with single site catalyst formulationsare lower relative to ethylene interpolymers produced with heterogeneouscatalyst formulations. Thus, in the embodiments disclosed, the firstethylene interpolymer has a lower M_(w)/M_(n) relative to the secondethylene interpolymer; where the second ethylene interpolymer isproduced with a heterogeneous catalyst formulation. The upper limit onthe M_(w)/M_(n) of the first ethylene interpolymer may be about 2.8, inother cases about 2.5 and in still other cases about 2.2. The lowerlimit on the M_(w)/M_(n) the first ethylene interpolymer may be about1.7, in other cases about 1.8 and in still other cases about 1.9.

The first ethylene interpolymer contains catalyst residues that reflectthe chemical composition of the single-site catalyst formulation used.Those skilled in the art will understand that catalyst residues aretypically quantified by the parts per million of metal in the firstethylene interpolymer, where metal refers to the metal in component (i),i.e., the metal in the “bulky ligand-metal complex”; hereafter (and inthe claims) this metal will be referred to “metal A”. As recited earlierin this disclosure, non-limiting examples of metal A include Group 4metals, titanium, zirconium and hafnium. The upper limit on the ppm ofmetal A in the first ethylene interpolymer may be about 1.0 ppm, inother cases about 0.9 ppm and in still other cases about 0.8 ppm. Thelower limit on the ppm of metal A in the first ethylene interpolymer maybe about 0.01 ppm, in other cases about 0.1 ppm and in still other casesabout 0.2 ppm.

The amount of hydrogen added to R1 can vary over a wide range allowingthe continuous solution process to produce first ethylene interpolymersthat differ greatly in melt index, hereafter I₂ ¹ (melt index ismeasured at 190° C. using a 2.16 kg load following the proceduresoutlined in ASTM D1238). The quantity of hydrogen added to R1 isexpressed as the parts-per-million (ppm) of hydrogen in R1 relative tothe total mass in reactor R1; hereafter H₂R¹ (ppm). The upper limit onI₂ ¹ may be about 200 dg/min, in some cases about 100 dg/min; in othercases about 50 dg/min, and; in still other cases about 1 dg/min. Thelower limit on I₂ ¹ may be about 0.01 dg/min, in some cases about 0.05dg/min; in other cases about 0.1 dg/min, and; in still other cases about0.5 dg/min.

The upper limit on the weight percent (wt %) of the first ethyleneinterpolymer in the ethylene interpolymer product may be about 60 wt %,in other cases about 55 wt % and in still other cases about 50 wt %. Thelower limit on the wt % of the first ethylene interpolymer in theethylene interpolymer product may be about 15 wt %; in other cases about25 wt % and in still other cases about 30 wt %.

Second Ethylene Interpolymer

If optional α-olefin is not added to reactor 2 (R2) either by addingfresh α-olefin to R2 (or carried over from R1) then the ethyleneinterpolymer produced in R2 is an ethylene homopolymer. If an optionalα-olefin is present in R2, the following weight ratio is one parameterto control the density of the second ethylene interpolymer produced inR2: ((α-olefin)/(ethylene))R². Hereafter, the symbol “σ²” refers to thedensity of the ethylene interpolymer produced in R2. The upper limit onσ² may be about 0.975 g/cm³; in some cases about 0.965 g/cm³ and; inother cases about 0.955 g/cm³. Depending on the heterogeneous catalystformulation used, the lower limit on σ² may be about 0.89 g/cm³, in somecases about 0.90 g/cm³, and; in other cases about 0.91 g/cm³.

A heterogeneous catalyst formulation is used to produce the secondethylene interpolymer. If the second ethylene interpolymer contains anα-olefin, the CDBI₅₀ of the second ethylene interpolymer is lowerrelative to the CDBI₅₀ of the first ethylene interpolymer that wasproduced with a single-site catalyst formulation. In an embodiment ofthis disclosure, the upper limit on the CDBI₅₀ of the second ethyleneinterpolymer (that contains an α-olefin) may be about 70%, in othercases about 65% and in still other cases about 60%. In an embodiment ofthis disclosure, the lower limit on the CDBI₅₀ of the second ethyleneinterpolymer (that contains an α-olefin) may be about 45%, in othercases about 50% and in still other cases about 55%. If an α-olefin isnot added to the continuous solution polymerization process the secondethylene interpolymer is an ethylene homopolymer. In the case of ahomopolymer, which does not contain α-olefin, one can still measure aCDBI₅₀ using TREF. In the case of a homopolymer, the upper limit on theCDBI₅₀ of the second ethylene interpolymer may be about 98%, in othercases about 96% and in still other cases about 95%, and; the lower limiton the CDBI₅₀ may be about 88%, in other cases about 89% and in stillother cases about 90%. It is well known to those skilled in the art thatas the α-olefin content in the second ethylene interpolymer approacheszero, there is a smooth transition between the recited CDBI₅₀ limits forthe second ethylene interpolymers (that contain an α-olefin) and therecited CDBI₅₀ limits for the second ethylene interpolymers that areethylene homopolymers. Typically, the CDBI₅₀ of the first ethyleneinterpolymer is higher than the CDBI₅₀ of the second ethyleneinterpolymer.

The M_(w)/M_(n) of second ethylene interpolymer is higher than theM_(w)/M_(n) of the first ethylene interpolymer. The upper limit on theM_(w)/M_(n) of the second ethylene interpolymer may be about 4.4, inother cases about 4.2 and in still other cases about 4.0. The lowerlimit on the M_(w)/M_(n) of the second ethylene interpolymer may beabout 2.2. M_(w)/M_(n)'s of 2.2 are observed when the melt index of thesecond ethylene interpolymer is high, or when the melt index of theethylene interpolymer product is high, e.g. greater than 10 g/10minutes. In other cases the lower limit on the M_(w)/M_(n) of the secondethylene interpolymer may be about 2.4 and in still other cases about2.6.

The second ethylene interpolymer contains catalyst residues that reflectthe chemical composition of heterogeneous catalyst formulation. Thoseskilled in the art with understand that heterogeneous catalyst residuesare typically quantified by the parts per million of metal in the secondethylene interpolymer, where the metal refers to the metal originatingfrom component (vii), i.e., the “metal compound”; hereafter (and in theclaims) this metal will be referred to as “metal B”. As recited earlierin this disclosure, non-limiting examples of metal B include metalsselected from Group 4 through Group 8 of the Periodic Table, or mixturesof metals selected from Group 4 through Group 8. The upper limit on theppm of metal B in the second ethylene interpolymer may be about 12 ppm,in other cases about 10 ppm and in still other cases about 8 ppm. Thelower limit on the ppm of metal B in the second ethylene interpolymermay be about 0.5 ppm, in other cases about 1 ppm and in still othercases about 3 ppm. While not wishing to be bound by any particulartheory, in series mode of operation it is believed that the chemicalenvironment within the second reactor deactivates the single sitecatalyst formulation, or; in parallel mode of operation the chemicalenvironment within R2 deactivates the single site catalyst formation.

The amount of hydrogen added to R2 can vary over a wide range whichallows the continuous solution process to produce second ethyleneinterpolymers that differ greatly in melt index, hereafter I₂ ². Thequantity of hydrogen added is expressed as the parts-per-million (ppm)of hydrogen in R2 relative to the total mass in reactor R2; hereafterH₂R² (ppm). The upper limit on I₂ ² may be about 1000 dg/min; in somecases about 750 dg/min; in other cases about 500 dg/min, and; in stillother cases about 200 dg/min. The lower limit on I₂ ² may be about 0.3dg/min, in some cases about 0.4 dg/min, in other cases about 0.5 dg/min,and; in still other cases about 0.6 dg/min.

The upper limit on the weight percent (wt %) of the second ethyleneinterpolymer in the ethylene interpolymer product may be about 85 wt %,in other cases about 80 wt % and in still other cases about 70 wt %. Thelower limit on the wt % of the second ethylene interpolymer in theethylene interpolymer product may be about 30 wt %; in other cases about40 wt % and in still other cases about 50 wt %.

Third Ethylene Interpolymer

A third ethylene interpolymer is not produced in R3 if a catalystdeactivator is added upstream of R3. If a catalyst deactivator is notadded and optional α-olefin is not present then the third ethyleneinterpolymer produced in R3 is an ethylene homopolymer. If a catalystdeactivator is not added and optional α-olefin is present in R3, thefollowing weight ratio determines the density of the third ethyleneinterpolymer: ((α-olefin)/(ethylene))R³. In the continuous solutionpolymerization process ((α-olefin)/(ethylene))R³ is one of the controlparameter used to produce a third ethylene interpolymer with a desireddensity. Hereafter, the symbol “σ³” refers to the density of theethylene interpolymer produced in R3. The upper limit on σ³ may be about0.975 g/cm³; in some cases about 0.965 g/cm³ and; in other cases about0.955 g/cm³. Depending on the heterogeneous catalyst formulations used,the lower limit on σ³ may be about 0.89 g/cm³, in some cases about 0.90g/cm³, and; in other cases about 0.91 g/cm³. Optionally, a secondheterogeneous catalyst formulation may be added to R3.

Typically, the upper limit on the CDBI₅₀ of the optional third ethyleneinterpolymer (containing an α-olefin) may be about 65%, in other casesabout 60% and in still other cases about 55%. The CDBI₅₀ of an α-olefincontaining optional third ethylene interpolymer will be lower than theCDBI₅₀ of the first ethylene interpolymer produced with the single-sitecatalyst formulation. Typically, the lower limit on the CDBI₅₀ of theoptional third ethylene interpolymer (containing an α-olefin) may beabout 35%, in other cases about 40% and in still other cases about 45%.If an α-olefin is not added to the continuous solution polymerizationprocess the optional third ethylene interpolymer is an ethylenehomopolymer. In the case of an ethylene homopolymer the upper limit onthe CDBI₅₀ may be about 98%, in other cases about 96% and in still othercases about 95%, and; the lower limit on the CDBI₅₀ may be about 88%, inother cases about 89% and in still other cases about 90%. Typically, theCDBI₅₀ of the first ethylene interpolymer is higher than the CDBI₅₀ ofthe third ethylene interpolymer and second ethylene interpolymer.

The upper limit on the M_(w)/M_(n) of the optional third ethyleneinterpolymer may be about 5.0, in other cases about 4.8 and in stillother cases about 4.5. The lower limit on the M_(w)/M_(n) of theoptional third ethylene interpolymer may be about 2.2, in other casesabout 2.4 and in still other cases about 2.6. The M_(w)/M_(n) of theoptional third ethylene interpolymer is higher than the M_(w)/M_(n) ofthe first ethylene interpolymer. When blended together, the second andthird ethylene interpolymer have a fourth M_(w)/M_(n) which is notbroader than the M_(w)/M_(n) of the second ethylene interpolymer.

The catalyst residues in the optional third ethylene interpolymerreflect the chemical composition of the heterogeneous catalystformulation(s) used, i.e., the first and optionally a secondheterogeneous catalyst formulation. The chemical compositions of thefirst and second heterogeneous catalyst formulations may be the same ordifferent; for example a first component (vii) and a second component(vii) may be used to synthesize the first and second heterogeneouscatalyst formulation. As recited above, “metal B” refers to the metalthat originates from the first component (vii). Hereafter, “metal C”refers to the metal that originates from the second component (vii).Metal B and optional metal C may be the same, or different. Non-limitingexamples of metal B and metal C include metals selected from Group 4through Group 8 of the Periodic Table, or mixtures of metals selectedfrom Group 4 through Group 8. The upper limit on the ppm of (metalB+metal C) in the optional third ethylene interpolymer may be about 12ppm, in other cases about 10 ppm and in still other cases about 8 ppm.The lower limit on the ppm of (metal B+metal C) in the optional thirdethylene interpolymer may be about 0.5 ppm, in other cases about 1 ppmand in still other cases about 3 ppm.

Optionally, hydrogen may be added to R3. Adjusting the amount ofhydrogen in R3, hereafter H₂ ^(R3) (ppm), allows the continuous solutionprocess to produce third ethylene interpolymers that differ widely inmelt index, hereafter I₂ ³. The upper limit on I₂ ³ may be about 2000dg/min; in some cases about 1500 dg/min; in other cases about 1000dg/min, and; in still other cases about 500 dg/min. The lower limit onI₂ ³ may be about 0.5 dg/min, in some cases about 0.6 dg/min, in othercases about 0.7 dg/min, and; in still other cases about 0.8 dg/min.

The upper limit on the weight percent (wt %) of the optional thirdethylene interpolymer in the ethylene interpolymer product may be about30 wt %, in other cases about 25 wt % and in still other cases about 20wt %. The lower limit on the wt % of the optional third ethyleneinterpolymer in the ethylene interpolymer product may be 0 wt %; inother cases about 5 wt % and in still other cases about 10 wt %.

Ethylene Interpolymer Product

The upper limit on the density of the ethylene interpolymer productsuitable for rotomolded articles may be about 0.955 g/cm³; in some casesabout 0.953 g/cm³ and; in other cases about 0.950 g/cm³. The lower limiton the density of the ethylene interpolymer product suitable forrotomolded articles may be about 0.930 g/cm³, in some cases about 0.933g/cm³, and; in other cases about 0.935 g/cm³.

The upper limit on the CDBI₅₀ of the ethylene interpolymer product maybe about 97%, in other cases about 90% and in still other cases about85%. An ethylene interpolymer product with a CDBI₅₀ of 97% may result ifan α-olefin is not added to the continuous solution polymerizationprocess; in this case, the ethylene interpolymer product is an ethylenehomopolymer. The lower limit on the CDBI₅₀ of an ethylene interpolymermay be about 50%, in other cases about 55% and in still other casesabout 60%.

The upper limit on the M_(w)/M_(n) of the ethylene interpolymer productmay be about 6, in other cases about 5 and in still other cases about 4.The lower limit on the M_(w)/M_(n) of the ethylene interpolymer productmay be 2.0, in other cases about 2.2 and in still other cases about 2.4.

The catalyst residues in the ethylene interpolymer product reflect thechemical compositions of: the single-site catalyst formulation employedin R1; the first heterogeneous catalyst formulation employed in R2, and;optionally the first or optionally the first and second heterogeneouscatalyst formulation employed in R3. In this disclosure, catalystresidues were quantified by measuring the parts per million of catalyticmetal in the ethylene interpolymer products. In addition, the elementalquantities (ppm) of magnesium, chlorine and aluminum were quantified.Catalytic metals originate from two or optionally three sources,specifically: 1) “metal A” that originates from component (i) that wasused to form the single-site catalyst formulation; (2) “metal B” thatoriginates from the first component (vii) that was used to form thefirst heterogeneous catalyst formulation, and; (3) optionally “metal C”that originates from the second component (vii) that was used to formthe optional second heterogeneous catalyst formulation. Metals A, B andC may be the same or different. In this disclosure the term “totalcatalytic metal” is equivalent to the sum of catalytic metals A+B+C.Further, in this disclosure the terms “first total catalytic metal” and“second total catalyst metal” are used to differentiate between thefirst ethylene interpolymer product of this disclosure and a comparative“polyethylene composition” that were produced using different catalystformulations.

The upper limit on the ppm of metal A in the ethylene interpolymerproduct may be about 0.6 ppm, in other cases about 0.5 ppm and in stillother cases about 0.4 ppm. The lower limit on the ppm of metal A in theethylene interpolymer product may be about 0.001 ppm, in other casesabout 0.01 ppm and in still other cases about 0.03 ppm. The upper limiton the ppm of (metal B+metal C) in the ethylene interpolymer product maybe about 11 ppm, in other cases about 9 ppm and in still other casesabout 7 ppm. The lower limit on the ppm of (metal B+metal C) in theethylene interpolymer product may be about 0.5 ppm, in other cases about1 ppm and in still other cases about 3 ppm.

In some embodiments, ethylene interpolymers may be produced where thecatalytic metals (metal A, metal B and metal C) are the same metal; anon-limiting example would be titanium. In such embodiments, the ppm of(metal B+metal C) in the ethylene interpolymer product is calculatedusing equation (VII):ppm^((B+C))=((ppm^((A+B+C))−(f ^(A)×ppm^(A)))/(1−f ^(A))  (VII)

where: ppm^((B+C)) is the calculated ppm of (metal B+metal C) in theethylene interpolymer product; ppm^((A+B+c)) is the total ppm ofcatalyst residue in the ethylene interpolymer product as measuredexperimentally, i.e., (metal A ppm+metal B ppm+metal C ppm); f^(A)represents the weight fraction of the first ethylene interpolymer in theethylene interpolymer product, f^(A) may vary from about 0.15 to about0.6, and; ppm^(A) represents the ppm of metal A in the first ethyleneinterpolymer. In equation (VII) ppm^(A) is assumed to be 0.35 ppm.

Embodiments of the ethylene interpolymer products disclosed herein havelower catalyst residues relative to the polyethylene polymers describedin U.S. Pat. No. 6,277,931. Higher catalyst residues in U.S. Pat. No.6,277,931 increase the complexity of the continuous solutionpolymerization process; an example of increased complexity includesadditional purification steps to remove catalyst residues from thepolymer. In contrast, in the present disclosure, catalyst residues arenot removed. In this disclosure, the upper limit on the “total catalyticmetal”, i.e., the total ppm of (metal A ppm+metal B ppm+optional metal Cppm) in the ethylene interpolymer product may be about 11 ppm, in othercases about 9 ppm and in still other cases about 7, and; the lower limiton the total ppm of catalyst residuals (metal A+metal B+optional metalC) in the ethylene interpolymer product may be about 0.5 ppm, in othercases about 1 ppm and in still other cases about 3 ppm.

The upper limit on melt index of the ethylene interpolymer product maybe about 15 dg/min, in some cases about 14 dg/min; in other cases about12 dg/min, and; in still other cases about 10 dg/min. The lower limit onthe melt index of the ethylene interpolymer product may be about 0.5dg/min, in some cases about 0.6 dg/min; in other cases about 0.7 dg/min,and; in still other cases about 0.8 dg/min.

A computer generated ethylene interpolymer product is illustrated inTable 1; this simulations was based on fundamental kinetic models (withkinetic constants specific for each catalyst formulation) as well asfeed and reactor conditions. The simulation was based on theconfiguration of the solution pilot plant described below; which wasused to produce the examples of ethylene interpolymer products disclosedherein. Simulated Example 13 was synthesized using a single-sitecatalyst formulation (PIC-1) in R1 and an in-line Ziegler-Natta catalystformulation in R2 and R3. Table 1 discloses a non-limiting example ofthe density, melt index and molecular weights of the first, second andthird ethylene interpolymers produced in the three reactors (R1, R2 andR3); these three interpolymers are combined to produce Simulated Example13 (the ethylene polymer product). As shown in Table 1, the SimulatedExample 13 product has a density of 0.9169 g/cm³, a melt index of 1.0dg/min, a branch frequency of 12.1 (the number of C6-branches per 1000carbon atoms (1-octene comonomer)) and a M_(w)/M_(n) of 3.11. SimulatedExample 13 comprises: a first, second and third ethylene interpolymerhaving a first, second and third melt index of 0.31 dg/min, 1.92 dg/minand 4.7 dg/min, respectively; a first, second and third density of0.9087 g/cm³, 0.9206 g/cm³ and 0.9154 g/cm³, respectively; a first,second and third M_(w)/M_(n) of 2.03 M_(w)/M_(n), 3.29 M_(w)/M_(n) and3.28 M_(w)/M_(n), respectively, and; a first, second and third CDBI₅₀ of90 to 95%, 55 to 60% and 45 to 55%, respectively. The simulatedproduction rate of Simulated Example 13 was 90.9 kg/hr and the R3 exittemperature was 217.1° C.

Table 9 discloses two examples of ethylene interpolymer products(Example 71 and Example 73) suitable for rotomolding applications havingmelt indexes and densities of about 1.6 melt index and about 0.947g/cm³, respectively, and; Comparative Examples 16, 40 and 41 at similarmelt index and density. The samples disclosed in Table 9 were producedin a continuous solution pilot plant (as described in the Examplessection of this disclosure (below)). Continuous solution processconditions are summarized in Table 8. Example 71 and Example 73 wereproduced using a single site catalyst formulation in reactor 1 (R1) andan in-line Ziegler-Natta catalyst formulation in reactor 2 (R2).Comparative Examples 16, 40 and 41 were produced using a single sitecatalyst formulation in both R1 and R2.

GPC deconvolution results are summarized in Table 10. The first ethyleneinterpolymer was fit to a distribution based on a fundamental kineticmodel that describes the behavior of the single site catalystformulation. In the case of Examples 71 and 73, the second and thirdethylene interpolymer was fit to a distribution based on a fundamentalkinetic model that describes the behavior of the heterogeneous catalystformulation. Ethylene interpolymer product Example 73 contains: 30.9 wt% of a first ethylene interpolymer having a M_(w) of 181539 daltons anda polydispersity (M_(w)/M_(n)) of 2.06; 60.5 wt % of a second ethyleneinterpolymer having a M_(w) of 52488 daltons and a polydispersity of2.77, and; 8.5 wt % of a third ethylene interpolymer having a M_(w) of40436 daltons and a polydispersity of 2.52. Graphically, thedeconvolution of Example 73 can be seen in FIG. 7. Ethylene interpolymerproduct Example 71 contains: 35.6 wt % of a first ethylene interpolymerhaving a M_(w) of 174406 daltons and a polydispersity of 2.05; 56.5 wt %of a second ethylene interpolymer having a M_(w) of 45108 daltons and apolydispersity of 2.56, and; 7.9 wt % of a third ethylene interpolymerhaving a M_(w) of 34705 daltons and a polydispersity of 2.35.

Graphically, the deconvolution of Comparative Example 16 into twoethylene interpolymers can be seen in FIG. 8. As shown in Table 10,Comparative Example 16 contains: 29.6 wt % of a first ethyleneinterpolymer having a M_(w) of 204103 daltons and a polydispersity of2.0, and; 70.4 wt % of a second ethylene interpolymer having a M_(w) of44727 daltons and a polydispersity of 2.0. GPC deconvolution ofComparative Examples 40 and 41 are also summarized in Table 10.

Ethylene Interpolymer Products Suitable for Rotomolding

Tables 2A through 2C summarize process conditions that were used tomanufacture ethylene interpolymer product Example 62; as well asComparative Example 15. The production rate of Examples 62 was 12%higher relative to Comparative Example 15. As shown in Table 2A, Example62 was manufactured using a single-site catalyst formulation in reactor1, an in-line Ziegler-Natta catalyst formulations in reactor 2 and thein-line Ziegler-Natta catalyst produced a third ethylene interpolymer inreactor 3; the resulting ethylene interpolymer product was produced at95.2 kg/h. In contrast, in Comparative Example 15 a single-site catalystformulation was used in both reactors 1 and 2, producing “a comparativeethylene interpolymer”, comprising a first and second ethyleneinterpolymer, at a maximum production rate of 84.9 kg/hr. In bothExamples 62 and Comparative Example 15, reactors 1 and 2 were configuredin series, i.e., the effluent from reactor 1 flowed directly intoreactor 2.

Table 3 summarizes the density, melt flow properties and molecularweights of Example 62 and Comparative Example 15; the comonomer used was1-octene.

Table 4 compares additional physical properties of Example 62 andComparative Example 15; as well as Comparative O. Comparative O wasmanufactured on a commercial scale solution process facility.Comparative O was similar to Comparative Example 15 in that ComparativeO was manufactured using a single-site catalyst formulation. ComparativeO was produced in a series dual reactor solution process where asingle-site catalyst formulation was used in both reactors; i.e., thecommercial resin designated SURPASS® RMs341-U available from NOVAChemicals (Calgary, AB, Canada).

Example 62 and Comparative Example 15 were passed through a twin screwextruder where 1500 ppm of a UV (ultra violet) protective additive(Tinuvin 622, available from BASF Corporation, Florham Park, N.J.,U.S.A) was thoroughly blended into the ethylene interpolymer products.

Table 4 compares various physical properties of Example 62 withComparative Example 15 and Comparative O. As shown in FIG. 1, theethylene interpolymer product Example 62 has a higher 2% secant modulus(is stiffer) and has a higher ESCR relative to Comparative Example 15.The combination of higher stiffness and higher ESCR demonstrates theusefulness of the disclosed ethylene interpolymer products inrotomolding applications.

Table 8 summarizes the continuous solution process conditions that wereused to manufacture ethylene interpolymer product Example 71 and 73; aswell as Comparative Examples 16, 40 and 41. Examples 71 and 73 weremanufactured using a single-site catalyst formulation (PIC-1) in reactor1, an in-line Ziegler-Natta catalyst formulation in reactor 2 and thein-line Ziegler-Natta catalyst produced a third ethylene interpolymer inreactor 3. Table 10 discloses the M_(n), M_(w) and polydispersities(M_(w)/M_(n)) of the first, second and third ethylene interpolymers thatcomprise Examples 71 and 73. In Examples 71 and 73 reactors 1 and 2 wereconfigured in series, i.e. the effluent from reactor 1 flowed directlyinto reactor 2.

As shown in Table 8, Comparative Examples 16, 40 and 41 weremanufactured using a single-site catalyst formulation (PIC-1) in bothreactors 1 and 2. Comparative Examples 16, 40 and 41 are examples of “acomparative ethylene interpolymer synthesized using one or moresingle-site catalyst formulations”; as recited in the claims. Table 10discloses the M_(n), M_(w) and polydispersities (M_(w)/M_(n)) of thefirst and second ethylene interpolymers comprising Comparative Examples16, 40 and 41. In Comparative Examples 16, 40 and 41 the reactors (R1and R2) were configured in series.

The physical properties of pilot plant produced Examples 71 and 73 andComparative Examples 16, 40 and 41 are disclosed in Table 9, i.e.,density, melt index (I₂), melt flow ratio, stress exponent, branchfrequency/1000 C, mole % comonomer (1-octene), GPC (M_(n), M_(w), M_(z),M_(w)/M_(n) and M_(z)/M_(w)), TREF elution temperature (peaktemperature), and FTIR unsaturation data (internal, side chain andterminal unsaturation).

Pilot plant produced Example 71 and 73, as well as Comparative Examples16, 40 and 41, were passed through a twin screw extruder where 1500 ppmof a UV (ultra violet) protective additive (Tinuvin 622, available fromBASF Corporation, Florham Park, N.J., U.S.A) was thoroughly blended intothe ethylene interpolymer products.

Table 11 compares the flexural modulus (1% secant) and the ESCRproperties of compression molded plaques produced from Examples 71 and73 and Comparative Examples 16, 40 and 41; all samples contained the UVadditive. In this disclosure, compression molded plaque ESCR data wasused as a proxy for the ESCR performance of the wall structure of arotomolded part. Further, ESCR testing was employed as a pass/fail test.Specifically, the wall structure of a rotomolded part passed ESCR testCondition A100 if the failure time (F^(A) ₅₀) was 1000 hr, where F^(A)_(R)) was estimated graphically as described in Annex A1 of ASTM D1693;in contrast, the wall structure of a rotomolded part failed ESCR textCondition A100 if F^(A) ₅₀ was <1000 hr. Similarly, the wall structureof a rotomolded part passed ESCR test Condition B100 if the failure time(F^(B) ₅₀) was 1000 hr, where F^(B) ₅₀ was estimated graphically asdescribed in Annex A1 of ASTM D1693; in contrast, the wall structurefailed the ESCR text Condition B100 if F^(B) ₅₀ was <1000 hr. GivenTable 11, it is evident that Examples 71 and 72 passed the ESCR test(both Condition A100 and Condition B100); in contrast ComparativeExamples 16, 40 and 41 failed the ESCR test.

Table 12 compares the ESCR performance of Example 71 and Example 73 withComparative Examples 16, 40 and 41. In the case of Example 71 and 73passed the ESCR test. To be clear, in the case of Example 71 and 73 noneof the ESCR test specimens (10-specimens for each Example) failed after1000 hr of ESCR testing (in both ESCR Condition A100 and the ESCR B100)and the ESCR test was terminated after 1000 hr (41.7 days). In contrast,Comparative Example 16 failed at 544 hr using ESCR Condition A100 and at858 hr using ESCR Condition B100. Similarly, Comparative Example 40failed at 120 hr using ESCR Condition A100 and at 112 hr using ESCRCondition B100, and; Comparative Example 41 failed at 80 hr using ESCRCondition A100 and at 141 hr using ESCR Condition B100. Given Table 11,it is evident that Examples 71 and 73 have superior ESCR performancerelative to Comparative Examples 16, 40 and 41. Table 11 also comparesthe flexural modulus of Example 71 and Example 73 with ComparativeExamples 16, 40 and 41.

The ethylene interpolymer products (containing the UV additive) wereconverted into rotomolded parts using a rotational molding machine (seethe Testing Methods section of this disclosure). Cubical rotomoldedparts (12.5 inches (31.8 cm)×12.5 inches×12.5 inches) having a wallthickness of 0.25 inches (0.64 cm) were produced.

The low temperature impact properties of test specimens cut fromrotomolded parts were evaluated using the ARM impact test performed inaccordance with ASTM D5628 at a test temperature of −40° C. This testwas adapted from the Association of Rotational Molders International,Low Temperature Impact Test, Version 4.0 dated July 2003; hereinincorporated by reference. Table 12 compares the low temperature impactproperties of Example 71 and Example 73 with Comparative Examples 16, 40and 41. Note that the rotomolding conditions varied slightly, i.e. themolds and their contents were heated in the Rotospeed RS3-160 oven for20, 22 or 24 minutes. In the ARM Impact test, rotomolded specimens, 5inch×5 inch (12.7 cm×12.7 cm) were cut from a side wall of the cubicalrotomolded part. Test specimens were impact tested using a drop weightimpact tester at −40° C.±2° C. (−40° F.±3.5° F.), i.e., if a specimendid not fail at a given height and weight, either the height or weightwas increased incrementally until specimen failure occurred. Specimenfailures were characterized as a ductile or a brittle failure. Ductilefailure was characterized by penetration of the dart though the specimenand the impact area was elongated and thinned leaving a hole withstringy fibers at the point of failure. Brittle failure was evident whenthe test specimen cracked, where the cracks radiated outwardly frompoint of failure and the sample showed very little to no elongation atthe point of failure. The “ARM Ductility %” disclosed in Table 12 wascalculated as follows: 100×[(number of ductile failures)/(total numberof all failures)]. The “ARM Mean Failure Energy (ft·lbs)” disclosed inTable 12 was calculated by multiplying the drop height (ft) by thenominal dart weight (lbs).

In the ARM Impact test, a rotomolded part having an ARM Mean FailureEnergy equal to or greater than or equal to 120 lb·ft in combinationwith an ARM Ductility equal to or greater than or equal to 50% wasconsidered a good part, i.e. the rotomolded part passed the ARM Impacttest. To be clear, a wall structure having an ARM Mean Failure Energy120 lb·ft and an ARM Ductility 50% passed the ARM Impact test; incontrast, a wall structure having an ARM Mean Failure Energy <120 lb·ftor an ARM Ductility <50% failed the ARM Impact test.

Dilution Index (Y_(d)) of Ethylene Interpolymer Products

In FIG. 2 the Dilution Index (Y_(d), having dimensions of ° (degrees))and Dimensionless Modulus (X_(d)) are plotted for several embodiments ofthe ethylene interpolymer products disclosed herein (the solid symbols),as well as comparative ethylene interpolymer products, i.e., ComparativeA, D, E and S. Further, FIG. 2 defines the following three quadrants:

Type I: Y_(d)>−1.0 and X_(d)<0;

Type II: Y_(d)>0 and X_(d)>0, and;

Type III: Y_(d)<0 and X_(d)>0.

The Type I region is identified by the dotted rectangle in the upperleft quadrant of FIG. 2. The data plotted in FIG. 2 is also tabulated inTable 5. In FIG. 2, Comparative S (open triangle) was used as therheological reference in the Dilution Index test protocol. Comparative Sis an ethylene interpolymer product comprising an ethylene interpolymersynthesized using an in-line Ziegler-Natta catalyst in one solutionreactor, i.e., SCLAIR® FP120-C which is an ethylene/1-octeneinterpolymer available from NOVA Chemicals Company (Calgary, Alberta,Canada). Comparatives D and E (open diamonds, Y_(d)<0, X_(d)>0) areethylene interpolymer products comprising a first ethylene interpolymersynthesized using a single-site catalyst formation and a second ethyleneinterpolymer synthesized using a batch Ziegler-Natta catalystformulation employing a dual reactor solution process, i.e., Elite®5100G and Elite® 5400G, respectively, both ethylene/1-octeneinterpolymers available from The Dow Chemical Company (Midland, Mich.,USA). Comparative A (open square, Y_(d)>−1 and X_(d)<0) was an ethyleneinterpolymer product comprising a first and second ethylene interpolymersynthesized using a single-site catalyst formation in a dual reactorsolution process, i.e., SURPASS® FPs117-C which is an ethylene/1-octeneinterpolymer available from NOVA Chemicals Company (Calgary, Alberta,Canada). Comparative Example 41 (open circle, Y_(d)>−1 and X_(d)<0) wasan ethylene interpolymer product comprising a first and second ethyleneinterpolymer synthesized using a single-site catalyst formulation in adual reactor solution pilot plant.

The following defines the Dilution Index (Y_(d)) and DimensionlessModulus (X_(d)). In addition to having molecular weights, molecularweight distributions and branching structures, blends of ethyleneinterpolymers may exhibit a hierarchical structure in the melt phase. Inother words, the ethylene interpolymer components may be, or may not be,homogeneous down to the molecular level depending on interpolymermiscibility and the physical history of the blend. Such hierarchicalphysical structure in the melt is expected to have a strong impact onflow and hence on processing and converting; as well as the end-useproperties of manufactured articles. The nature of this hierarchicalphysical structure between interpolymers can be characterized.

The hierarchical physical structure of ethylene interpolymers can becharacterized using melt rheology. A convenient method can be based onthe small amplitude frequency sweep tests. Such rheology results areexpressed as the phase angle δ as a function of complex modulus G*,referred to as van Gurp-Palmen plots (as described in M. Van Gurp, J.Palmen, Rheol. Bull. (1998) 67(1): 5-8, and; Dealy J, Plazek D. Rheol.Bull. (2009) 78(2): 16-31). For a typical ethylene interpolymer, thephase angle δ increases toward its upper bound of 90° with G* becomingsufficiently low. A typical VGP plot is shown in FIG. 3. The VGP plotsare a signature of resin architecture. The rise of δ toward 90° ismonotonic for an ideally linear, monodisperse interpolymer. The δ(G*)for a branched interpolymer or a blend containing a branchedinterpolymer may show an inflection point that reflects the topology ofthe branched interpolymer (see S. Trinkle, P. Walter, C. Friedrich,Rheo. Acta (2002) 41: 103-113). The deviation of the phase angle δ fromthe monotonic rise may indicate a deviation from the ideal linearinterpolymer either due to presence of long chain branching if theinflection point is low (e.g., δ≦20°) or a blend containing at least twointerpolymers having dissimilar branching structure if the inflectionpoint is high (e.g., δ≧70°).

For commercially available linear low density polyethylenes, inflectionpoints are not observed; with the exception of some commercialpolyethylenes that contain a small amount of long chain branching (LCB).To use the VGP plots regardless of presence of LCB, an alternative is touse the point where the frequency ω_(c) is two decades below thecross-over frequency ω_(c), i.e., ω_(c)=0.01ω_(x). The cross-over pointis taken as the reference as it is known to be a characteristic pointthat correlates with MI, density and other specifications of an ethyleneinterpolymer. The cross-over modulus is related to the plateau modulusfor a given molecular weight distribution (see S. Wu. J Polym Sci, PolymPhys Ed (1989) 27:723; M. R. Nobile, F. Cocchini. Rheol Acta (2001)40:111). The two decade shift in phase angle δ is to find the comparablepoints where the individual viscoelastic responses of constituents couldbe detected; to be more clear, this two decade shift is shown in FIG. 4.The complex modulus G*_(c) for this point is normalized to thecross-over modulus, G*_(x)/(√{square root over (2)}), as (√{square rootover (2)})G*_(c)/G*_(x), to minimize the variation due to overallmolecular weight, molecular weight distribution and the short chainbranching. As a result, the coordinates on VGP plots for this lowfrequency point at ω_(c)=0.01ω_(x), namely (√{square root over(2)})G*_(c)/G*_(x) and δ_(c′) characterize the contribution due toblending. Similar to the inflection points, the closer the ((√{squareroot over (2)})G*_(c)/G*_(x), δ_(c)) point is toward the 90° upperbound, the more the blend behaves as if it were an ideal singlecomponent.

As an alternative way to avoid interference due to the molecular weight,molecular weight distribution and the short branching of the ethyleneδ_(c) interpolymer ingredients, the coordinates (G_(c)*, δ_(c)) arecompared to a reference sample of interest to form the following twoparameters:

“Dilution Index (Y_(d))”Y _(d)=δ_(c)−(C ₀ −C ₁ e ^(C) ² ^(lnG*) ^(c) )

“Dimensionless Modulus (X_(d))”X _(d) =G* _(0.01ω) _(c) /G* _(r)

The constants C₀, C₁, and C₂ are determined by fitting the VGP dataδ(G*) of the reference sample to the following equation:δ=C ₀ −C ₁ e ^(C) ² ^(lnG*)

G*_(r) is the complex modulus of this reference sample at itsδ_(c)=δ(0.01ω_(x)). When an ethylene interpolymer, synthesized with anin-line Ziegler-Natta catalyst employing one solution reactor, having adensity of 0.920 g/cm³ and a melt index (MI or I₂) of 1.0 dg/min istaken as a reference sample, the constants are:

C₀=93.43°

C₁=1.316°

C₂=0.2945

G*_(r)=9432 Pa.

The values of these constants can be different if the rheology testprotocol differs from that specified herein.

These regrouped coordinates (X_(d), Y_(d)) from (G*_(c), δ_(c)) allowscomparison between ethylene interpolymer products disclosed herein withComparative examples. The Dilution Index (Y_(d)) reflects whether theblend behaves like a simple blend of linear ethylene interpolymers(lacking hierarchical structure in the melt) or shows a distinctiveresponse that reflects a hierarchical physical structure within themelt. The lower the Y_(d), the more the sample shows separate responsesfrom the ethylene interpolymers that comprise the blend; the higher theY_(d) the more the sample behaves like a single component, or singleethylene interpolymer.

Returning to FIG. 2: Type I (upper left quadrant) ethylene interpolymerproducts of this disclosure (solid circles) have Y_(d)>−1 and X_(d)<0;in contrast, Type III (lower right quadrant) comparative ethyleneinterpolymers Comparative D and E have Y_(d)<0 and X_(d)>0. In the caseof Type I ethylene interpolymer products (solid circles), the firstethylene interpolymer (single-site catalyst) and the second ethyleneinterpolymer (in-line Ziegler Natta catalyst) behave as a simple blendof two ethylene interpolymers and a hierarchical structure within themelt does not exist. However, in the case of Comparatives D and E (opendiamonds), the melt comprising a first ethylene interpolymer(single-site catalyst) and a second ethylene interpolymer (batch ZieglerNatta catalyst) possesses a hierarchical structure.

The ethylene interpolymer products of this disclosure fall into thequadrant Type I (Y_(d)>−1, X_(d)<0). The Dimensionless Modulus (X_(d)),reflects differences (relative to the reference sample) that are relatedto the overall molecular weight, molecular weight distribution(M_(w)/M_(n)) and short chain branching. Not wishing to be bound bytheory, conceptually, the Dimensionless Modulus (X_(d)) may beconsidered to be related to the M_(w)/M_(n) and the radius of gyration(<R_(g)>²) of the ethylene interpolymer in the melt; conceptually,increasing X_(d) has similar effects as increasing M_(w)/M_(n) and/or<R_(g)>², without the risk of including lower molecular weight fractionand sacrificing certain related properties.

Relative to film grade Comparative A (recall that Comparative Acomprises a first and second ethylene interpolymer synthesized with asingle-site catalyst) the solution process disclosed herein enables themanufacture of ethylene interpolymer products having higher X_(d). Notwishing to be bound by theory, as X_(d) increases the macromolecularcoils of higher molecular weight fraction are more expanded(conceptually higher <R_(g)>²) and upon crystallization the probabilityof tie chain formation is increased resulting in higher toughnessproperties; the polyethylene art is replete with disclosures thatcorrelate higher toughness with an increasing probability of tie chainformation.

In the Dilution Index testing protocol, the upper limit on Y_(d) may beabout 20, in some cases about 15 and is other cases about 13. The lowerlimit on Y_(d) may be about −30, in some cases −25, in other cases −20and in still other cases −15.

In the Dilution Index testing protocol, the upper limit on X_(d) is 1.0,in some cases about 0.95 and in other cases about 0.9. The lower limiton X_(d) is −2, in some cases −1.5 and in still other cases −1.0.

Terminal Vinyl Unsaturation of Ethylene Interpolymer Products

The ethylene interpolymer products of this disclosure are furthercharacterized by a terminal vinyl unsaturation greater than or equal to0.03 terminal vinyl groups per 100 carbon atoms (≧0.03 terminalvinyls/100 C); as determine via Fourier Transform Infrared (FTIR)spectroscopy according to ASTM ASTM D3124-98 and ASTM D6248-98.

FIG. 5 compares the terminal vinyl/100 C content of the ethyleneinterpolymers of this disclosure with several Comparatives. The datashown in FIG. 5 is also tabulated in Tables 6A and 6B. All of thecomparatives in FIG. 5 and Tables 6A and 6B are Elite® productsavailable from The Dow Chemical Company (Midland, Mich., USA); Eliteproducts are ethylene interpolymers produced in a dual reactor solutionprocess and comprise an interpolymer synthesized using a single-sitecatalyst and an interpolymer synthesized using a batch Ziegler-Nattacatalyst: Comparative B is Elite 5401G; Comparative C is Elite 5400G;Comparative E and E2 are Elite 5500G; Comparative G is Elite 5960;Comparative H and H2 are Elite 5100G; Comparative I is Elite 5940G, and;Comparative J is Elite 5230G.

As shown in FIG. 5 the average terminal vinyl content in the ethyleneinterpolymer of this disclosure was 0.045 terminal vinyls/100 C; incontrast, the average terminal vinyl content in the Comparative sampleswas 0.023 terminal vinyls/100 C. Statistically, at the 99.999%confidence level, the ethylene interpolymers of this disclosure aresignificantly different from the Comparatives; i.e. a t-Test assumingequal variances shows that the means of the two populations (0.045 and0.023 terminal vinyls/100 C) are significantly different at the 99.999%confidence level (t(obs)=12.891>3.510 t(crit two tail); orp-value=4.84×10⁻¹⁷<0.001 α (99.999% confidence)).

Catalyst Residues (Total Catalytic Metal)

The ethylene interpolymer products of this disclosure are furthercharacterized by having ≧3 parts per million (ppm) of total catalyticmetal (Ti); where the quantity of catalytic metal was determined byNeutron Activation Analysis (N.A.A.) as specified herein.

FIG. 6 compares the total catalytic metal content of the disclosedethylene interpolymers with several Comparatives; FIG. 6 data is alsotabulated in Tables 7A and 7B. All of the comparatives in FIG. 6 andTables 7A and 7B are Elite® products available from The Dow ChemicalCompany (Midland, Mich., USA), for additional detail see the sectionabove.

As shown in FIG. 6 the average total catalytic metal content in theethylene interpolymers of this disclosure was 7.02 ppm of titanium; incontrast, the average total catalytic metal content in the Comparativesamples was 1.63 ppm of titanium. Statistically, at the 99.999%confidence level, the ethylene interpolymers of this disclosure aresignificantly different from the Comparatives, i.e., a t-Test assumingequal variances shows that the means of the two populations (7.02 and1.63 ppm titanium) are significantly different at the 99.999% confidencelevel, i.e. (t(obs)=12.71>3.520 t(crit two tail); orp-value=1.69×10⁻¹⁶<0.001 α (99.999% confidence)).

Rigid Manufactured Articles

There is a need to improve the Environmental Stress Crack Resistance(ESCR) rotomolding articles, while maintaining or increasing stiffnessand retaining impact properties. The ethylene interpolymer productsdisclosed are well suited to accomplish this challenging combination ofproperties.

Additional non-limiting applications where the disclosed ethyleneinterpolymer may be used include: deli containers, margarine tubs,trays, cups, lids, bottles, bottle cap liners, pails, crates, drums,bumpers, industrial bulk containers, industrial vessels, materialhandling containers, playground equipment, recreational equipment,safety equipment, wire and cable applications (power cables,communication cables and conduits), tubing and hoses, pipe applications(pressure pipe and non-pressure pipe, e.g., natural gas distribution,water mains, interior plumbing, storm sewer, sanitary sewer, corrugatedpipes and conduit), foamed articles (foamed sheet or bun foam), militarypackaging (equipment and ready meals), personal care packaging (diapersand sanitary products), cosmetic, pharmaceutical and medical packaging,truck bed liners, pallets and automotive dunnage. Such rigidmanufactured articles may be fabricated using the conventional injectionmolding, compression molding and blow molding techniques. The desiredphysical properties of rigid manufactured articles depend on theapplication of interest. Non-limiting examples of desired propertiesinclude: flexural modulus (1% and 2% secant modulus); tensile toughness;environmental stress crack resistance (ESCR); slow crack growthresistance (PENT); abrasion resistance; shore hardness; heat deflectiontemperature (HDT); VICAT softening point; IZOD impact strength; ARMimpact resistance; Charpy impact resistance, and; color (whitenessand/or yellowness index). Rigid manufactured articles also includerotomolded articles, examples of the ethylene interpolymer productsdisclosed herein are suitable to manufacture rotomolded articles havingimproved stiffness and similar or improved ESCR relative to comparativeethylene interpolymer products.

Additives and Adjuvants

The ethylene interpolymer products and the manufactured rotomoldedarticles described above may optionally include, depending on itsintended use, additives and adjuvants. Non-limiting examples ofadditives and adjuvants include, anti-blocking agents, antioxidants,heat stabilizers, slip agents, processing aids, anti-static additives,colorants, dyes, filler materials, light stabilizers, heat stabilizers,light absorbers, lubricants, pigments, plasticizers, nucleating agentsand combinations thereof.

Testing Methods

Prior to testing, each specimen was conditioned for at least 24 hours at23±2° C. and 50±10% relative humidity and subsequent testing wasconducted at 23±2° C. and 50±10% relative humidity. Herein, the term“ASTM conditions” refers to a laboratory that is maintained at 23±2° C.and 50±10% relative humidity; and specimens to be tested wereconditioned for at least 24 hours in this laboratory prior to testing.ASTM refers to the American Society for Testing and Materials.

Density

Ethylene interpolymer product densities were determined using ASTMD792-13 (Nov. 1, 2013).

Melt Index

Ethylene interpolymer product melt index was determined using ASTM D1238(Aug. 1, 2013). Melt indexes, I₂, I₆, I₁₀ and I₂₁ were measured at 190°C., using weights of 2.16 kg, 6.48 kg, 10 kg and a 21.6 kg respectively.Herein, the term “stress exponent” or its acronym “S.Ex.”, is defined bythe following relationship:S.Ex.=log(I ₆ /I ₂)/log(6480/2160)

wherein I₆ and I₂ are the melt flow rates measured at 190° C. using 6.48kg and 2.16 kg loads, respectively. In this disclosure, melt index wasexpressed using the units of g/10 minutes or g/10 min or dg/minutes ordg/min; these units are equivalent.

Environmental Stress Crack Resistance (ESCR)

ESCR was determined according to ASTM D1693-13 (Nov. 1, 2013); hereinincorporated by reference. Both ESCR Condition A and B were employed. InCondition A the specimen thickness was within the range of 3.00 to 3.30mm (0.120 to 0.130 in) and the notch depth was within the range of 0.50to 0.65 mm (0.020 to 0.025 in). Condition A was conducted using 100%Igepal CO-630 (nonylphenoxy polyoxyethylene nonylphenylether). InCondition B the specimen thickness was within the range of 1.84 to 1.97mm (0.0725 to 0.0775 in) and a notch depth was within the range of 0.30to 0.40 mm (0.012 to 0.015 in). Condition B experiments were conductedusing 100% Igepal CO-630 or a solution of 10% Igepal CO-630 in water.

Gel Permeation Chromatography (GPC)

Ethylene interpolymer product molecular weights, M_(n), M_(w) and M_(z),as well the as the polydispersity (M_(w)/M_(n)), were determined usingASTM D6474-12 (Dec. 15, 2012). Ethylene interpolymer product samplesolutions (1 to 2 mg/mL) were prepared by heating the interpolymer in1,2,4-trichlorobenzene (TCB) and rotating on a wheel for 4 hours at 150°C. in an oven. The antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT)was added to the mixture in order to stabilize the interpolymer againstoxidative degradation. The BHT concentration was 250 ppm. Samplesolutions were chromatographed at 140° C. on a PL 220 high-temperaturechromatography unit equipped with four Shodex columns (HT803, HT804,HT805 and HT806) using TCB as the mobile phase with a flow rate of 1.0mL/minute, with a differential refractive index (DRI) as theconcentration detector. BHT was added to the mobile phase at aconcentration of 250 ppm to protect GPC columns from oxidativedegradation. The sample injection volume was 200 μL. The GPC raw datawere processed with the Cirrus GPC software. The GPC columns werecalibrated with narrow distribution polystyrene standards. Thepolystyrene molecular weights were converted to polyethylene molecularweights using the Mark-Houwink equation, as described in ASTM D6474-12(Dec. 15, 2012).

Unsaturation Content

The quantity of unsaturated groups, i.e., double bonds, in an ethyleneinterpolymer product was determined according to ASTM D3124-98(vinylidene unsaturation, published March 2011) and ASTM D6248-98 (vinyland trans unsaturation, published July 2012). An ethylene interpolymersample was: a) first subjected to a carbon disulfide extraction toremove additives that may interfere with the analysis; b) the sample(pellet, film or granular form) was pressed into a plaque of uniformthickness (0.5 mm), and; c) the plaque was analyzed by FTIR.

Comonomer Content

The quantity of comonomer in an ethylene interpolymer product wasdetermined by FTIR (Fourier Transform Infrared spectroscopy) accordingto ASTM D6645-01 (published January 2010).

Composition Distribution Branching Index (CDBI)

The “Composition Distribution Branching Index” or “CDBI” of thedisclosed Examples and Comparative Examples were determined using acrystal-TREF unit commercially available form Polymer ChAR (Valencia,Spain). The acronym “TREF” refers to Temperature Rising ElutionFractionation. A sample of ethylene interpolymer product (80 to 100 mg)was placed in the reactor of the Polymer ChAR crystal-TREF unit, thereactor was filled with 35 ml of 1,2,4-trichlorobenzene (TCB), heated to150° C. and held at this temperature for 2 hours to dissolve the sample.An aliquot of the TCB solution (1.5 mL) was then loaded into the PolymerChAR TREF column filled with stainless steel beads and the column wasequilibrated for 45 minutes at 110° C. The ethylene interpolymer productwas then crystallized from the TCB solution, in the TREF column, byslowly cooling the column from 110° C. to 30° C. using a cooling rate of0.09° C. per minute. The TREF column was then equilibrated at 30° C. for30 minutes. The crystallized ethylene interpolymer product was theneluted from the TREF column by passing pure TCB solvent through thecolumn at a flow rate of 0.75 mL/minute as the temperature of the columnwas slowly increased from 30° C. to 120° C. using a heating rate of0.25° C. per minute. Using Polymer ChAR software a TREF distributioncurve was generated as the ethylene interpolymer product was eluted fromthe TREF column, i.e., a TREF distribution curve is a plot of thequantity (or intensity) of ethylene interpolymer eluting from the columnas a function of TREF elution temperature. A CDBI₅₀ was calculated fromthe TREF distribution curve for each ethylene interpolymer productanalyzed. The “CDBI₅₀” is defined as the percent of ethyleneinterpolymer whose composition is within 50% of the median comonomercomposition (25% on each side of the median comonomer composition); itis calculated from the TREF composition distribution curve and thenormalized cumulative integral of the TREF composition distributioncurve. Those skilled in the art will understand that a calibration curveis required to convert a TREF elution temperature to comonomer content,i.e., the amount of comonomer in the ethylene interpolymer fraction thatelutes at a specific temperature. The generation of such calibrationcurves are described in the prior art, e.g., Wild, et al., J. Polym.Sci., Part B, Polym. Phys., Vol. 20 (3), pages 441-455: hereby fullyincorporated by reference.

Heat Deflection Temperature

The heat deflection temperature of an ethylene interpolymer product wasdetermined using ASTM D648-07 (approved Mar. 1, 2007). The heatdeflection temperature is the temperature at which a deflection toolapplying 0.455 MPa (66 PSI) stress on the center of a molded ethyleneinterpolymer plaque (3.175 mm (0.125 in) thick) causes it to deflect0.25 mm (0.010 in) as the plaque is heated in a medium at a constantrate.

Vicat Softening Point (Temperature)

The Vicat softening point of an ethylene interpolymer product wasdetermined according to ASTM D1525-07 (published December 2009). Thistest determines the temperature at which a specified needle penetrationoccurs when samples are subjected to ASTM D1525-07 test conditions,i.e., heating Rate B (120±10° C./hr and 938 gram load (10±0.2N load).

Neutron Activation Analysis (NAA)

Neutron Activation Analysis, hereafter NAA, was used to determinecatalyst residues in ethylene interpolymers and was performed asfollows. A radiation vial (composed of ultrapure polyethylene, 7 mLinternal volume) was filled with an ethylene interpolymer product sampleand the sample weight was recorded. Using a pneumatic transfer systemthe sample was placed inside a SLOWPOKE™ nuclear reactor (Atomic Energyof Canada Limited, Ottawa, Ontario, Canada) and irradiated for 30 to 600seconds for short half-life elements (e.g., Ti, V, Al, Mg, and Cl) or 3to 5 hours for long half-life elements (e.g., Zr, Hf, Cr, Fe and Ni).The average thermal neutron flux within the reactor was 5×10¹¹/cm²/s.After irradiation, samples were withdrawn from the reactor and aged,allowing the radioactivity to decay; short half-life elements were agedfor 300 seconds or long half-life elements were aged for several days.After aging, the gamma-ray spectrum of the sample was recorded using agermanium semiconductor gamma-ray detector (Ortec model GEM55185,Advanced Measurement Technology Inc., Oak Ridge, Tenn., USA) and amultichannel analyzer (Ortec model DSPEC Pro). The amount of eachelement in the sample was calculated from the gamma-ray spectrum andrecorded in parts per million relative to the total weight of theethylene interpolymer sample. The N.A.A. system was calibrated withSpecpure standards (1000 ppm solutions of the desired element (greaterthan 99% pure)). One mL of solutions (elements of interest) werepipetted onto a 15 mm×800 mm rectangular paper filter and air dried. Thefilter paper was then placed in a 1.4 mL polyethylene irradiation vialand analyzed by the N.A.A. system. Standards are used to determine thesensitivity of the N.A.A. procedure (in counts/μg).

Color Index

The Whiteness Index (WI) and Yellowness Index (YI) of ethyleneinterpolymer products were measured according to ASTM E313-10 (approvedin 2010) using a BYK Gardner Color-View colorimeter.

Dilution Index (Y_(d)) Measurements

A series of small amplitude frequency sweep tests were run on eachsample using an Anton Paar MCR501 Rotational Rheometer equipped with the“TruGap™ Parallel Plate measuring system”. A gap of 1.5 mm and a strainamplitude of 10% were used throughout the tests. The frequency sweepswere from 0.05 to 100 rad/s at the intervals of seven points per decade.The test temperatures were 170°, 190°, 210° and 230° C. Master curves at190° C. were constructed for each sample using the Rheoplus/32 V3.40software through the Standard TTS (time-temperature superposition)procedure, with both horizontal and vertical shift enabled.

The Y_(d) and X_(d) data generated are summarized in Table 5. The flowproperties of the ethylene interpolymer products, e.g., the meltstrength and melt flow ratio (MFR) are well characterized by theDilution Index (Y_(d)) and the Dimensionless Modulus (X_(d)) as detailedbelow. In both cases, the flow property is a strong function of Y_(d)and X_(d) in addition a dependence on the zero-shear viscosity. Forexample, the melt strength (hereafter MS) values of the disclosedExamples and the Comparative Examples were found to follow the sameequation, confirming that the characteristic VGP point ((√{square rootover (2)})G*_(c)/G*_(x), δ_(c)) and the derived regrouped coordinates(X_(d), Y_(d)) represent the structure well:MS=a ₀₀ +a ₁₀ log η₀ −a ₂₀(90−δ_(c))−a ₃₀((√{square root over (2)})G*_(c) /G* _(x))−a ₄₀(90−δ_(c))((√{square root over (2)})G* _(c) /G* _(x))

where

a₀₀=−33.33; a₁₀=9.529; a₂₀=0.03517; a₃₀=0.894; a₄₀=0.02969

and r²=0.984 and the average relative standard deviation was 0.85%.Further, this relation can be expressed in terms of the Dilution Index(Y_(d)) and the Dimensionless Modulus (X_(d)):MS=a ₀ +a ₁ log η₀ +a ₂ Y _(d) +a ₃ X _(d) +a ₄ Y _(d) X _(d)

where

a₀=33.34; a₁=9.794; a₂=0.02589; a₃=0.1126; a₄=0.03307

and r²=0.989 and the average relative standard deviation was 0.89%.

The MFR of the disclosed Examples and the Comparative samples were foundto follow a similar equation, further confirming that the dilutionparameters Y_(d) and X_(d) show that the flow properties of thedisclosed Examples differ from the reference and Comparative Examples:MFR=b ₀ −b ₁ log η₀ −b ₂ Y _(d) −b ₃ X _(d)

where

b₀=53.27; b₁=6.107; b₂=1.384; b₃=20.34

and r²=0.889 and the average relative standard deviation and 3.3%.

Further, the polymerization process and catalyst formulations disclosedherein allow the production of ethylene interpolymer products that canbe converted into flexible manufactured articles that have a desiredbalance of physical properties (i.e., several end-use properties can bebalanced (as desired) through multidimensional optimization); relativeto comparative polyethylenes of comparable density and melt index.

Tensile Properties

The following tensile properties were determined using ASTM D882-12(Aug. 1, 2012): tensile break strength (MPa), elongation at yield (%),yield strength (MPa), ultimate elongation (%), ultimate strength (MPa)and 1 and 2% secant modulus (MPa)

Flexural Properties

Flexural properties, i.e., 2% flexural secant modulus was determinedusing ASTM D790-10 (published in April 2010).

Hexane Extractables

Hexane extractables was determined according to the Code of FederalRegistration 21 CFR §177.1520 Para (c) 3.1 and 3.2; wherein the quantityof hexane extractable material in a sample is determinedgravimetrically.

ARM Impact Testing

The ARM impact test was performed in accordance with ASTM D5628, hereinincorporated by reference, at a test temperature of −40° C. This testwas adapted from the Association of Rotational Molders International,Low Temperature Impact Test, Version 4.0 dated July 2003; hereinincorporated by reference. The purpose of this test was to determine theimpact properties of the rotomolded parts. ARM Impact test specimens, 5inch×5 inch (12.7 cm×12.7 cm) were cut from a side wall of the cubicalrotomolded part. Test specimens were thermally equilibrated in arefrigerated testing laboratory maintained at −40° F.±3.5° F. (−40°C.±2° C.) for at least 24 hours prior to impact testing. The testingtechnique employed is commonly called the Bruceton Staircase Method orthe Up-and-Down Method. The procedure establishes the height of aspecific dart that will cause 50% of the specimens to fail, i.e. testing(dart falling on specimens) was carried out until there was a minimum of10 passes and 10 fails. Each failure was characterized as a ductile or abrittle failure. Ductile failure was characterized by penetration of thedart though the specimen and the impact area was elongated and thinnedleaving a hole with stringy fibers at the point of failure. Brittlefailure was evident when the test specimen cracked, where the cracksradiated outwardly from point of failure and the sample showed verylittle to no elongation at the point of failure. The “ARM Ductility %”was calculated as follows: 100×[(number of ductile failures)/(totalnumber of all failures)].

Samples were impact tested using a drop weight impact tester; impactdarts available consisted of 10 lb (4.54 kg), 15 lb (6.80 kg), 20 lb(9.07 kg) or 30 lb (13.6 kg) darts. All impact darts had a rounded darttip having a diameter of 1.0±0.005 inch (2.54 cm), the dart tiptransitioned into a lower cylindrical shaft (1.0 inch diameter), thelength of the lower cylindrical shaft (to dart tip) was 4.5 inch (11.4cm). Impact dart included an upper cylindrical shaft having a diameterof 2.0 inch (5.08 cm), the length of the upper cylinder shaft varieddepending on the desired weight of the dart, e.g. 10.5 inch (26.7 cm) or16.5 inch (41.9 cm) for the 10 lb or 20 lb dart, respectively.Preferably a dart weight is selected such that the drop height isbetween 2.5 ft and 7.5 ft (0.8 m to 2.3 m). Test specimens were orientedin the impact tester such that the falling dart impacted the surface ofthe part that was in contact with the mold (when molded). If the sampledid not fail at a given height and weight, either the height or weightwas increased incrementally until part failure occurred. Once failureoccurred, the height or weight is decreased by the same increment andthe process is repeated. The “ARM Mean Failure Energy (ft·lbs)” wascalculated by multiplying the drop height (ft) by the nominal dartweight (lbs). After impact, both the upper and lower surface of thespecimen were inspected for failure. For the ethylene interpolymerproducts disclosed herein, a ductile failure was desired failure mode.In the ARM Impact test, a rotomolded part having an ARM Mean FailureEnergy equal to or greater than or equal to 120 lb·ft in combinationwith an ARM Ductility equal to or greater than or equal to 50% wasconsidered a good part, i.e. the part passed the ARM Impact test. To beclear, a wall structure having an ARM Mean Failure Energy≧120 lb·ft andan ARM Ductility≧50% passed the ARM Impact test. In contrast, a wallstructure having an ARM Mean Failure Energy <120 lb·ft or an ARMDuctility <50% failed the ARM Impact test.

EXAMPLES

Polymerization

The following examples are presented for the purpose of illustratingselected embodiments of this disclosure; it being understood, that theexamples presented do not limit the claims presented.

Embodiments of ethylene interpolymer products described herein wereproduced in a continuous solution polymerization pilot plant comprisingreactors arranged in a series configuration. Methylpentane was used asthe process solvent (a commercial blend of methylpentane isomers). Thevolume of the first CSTR reactor (R1) was 3.2 gallons (12 L), the volumeof the second CSTR reactor (R2) was 5.8 gallons (22 L) and the volume ofthe tubular reactor (R3) was 4.8 gallons (18 L). Examples of ethyleneinterpolymer products were produced using an R1 pressure from about 14MPa to about 18 MPa; R2 was operated at a lower pressure to facilitatecontinuous flow from R1 to R2. R1 and R2 were operated in series mode,wherein the first exit stream from R1 flows directly into R2. BothCSTR's were agitated to give conditions in which the reactor contentswere well mixed. The process was operated continuously by feeding freshprocess solvent, ethylene, 1-octene and hydrogen to the reactors.

The single site catalyst components used were: component (i),cyclopentadienyl tri(tertiary butyl)phosphinimine titanium dichloride,(Cp[(t-Bu)₃PN]TiCl₂), hereafter PIC-1; component (ii), methylaluminoxane(MAO-07); component (iii), trityl tetrakis(pentafluoro-phenyl)borate,and; component (iv), 2,6-di-tert-butyl-4-ethylphenol. The single sitecatalyst component solvents used were methylpentane for components (ii)and (iv) and xylene for components (i) and (iii). The quantity of PIC-1added to R1, “R1 (i) (ppm)” is shown in Table 2A; to be clear, inExample 62 in Table 2A, the solution in R1 contained 0.20 ppm ofcomponent (i), i.e., PIC-1. The mole ratios of the single site catalystcomponents employed to produce Example 62 were: R1 (ii)/(i) moleratio=100, i.e. [(MAO-07)/(PIC-1)]; R1 (iv)/(ii) mole ratio=0.0, i.e.,[(2,6-di-tert-butyl-4-ethylphenol)/(MAO-07)], and; R1 (iii)/(i) moleratio=1.1, i.e., [(trityl tetrakis(pentafluoro-phenyOborate)/(PIC-1)].The single site catalyst formulation was injected into R1 using processsolvent, the flow rate of this catalyst containing solvent was about 30kg/hr.

The in-line Ziegler-Natta catalyst formulation was prepared from thefollowing components: component (v), butyl ethyl magnesium; component(vi), tertiary butyl chloride; component (vii), titanium tetrachloride;component (viii), diethyl aluminum ethoxide, and; component (ix),triethyl aluminum. Methylpentane was used as the catalyst componentsolvent. The in-line Ziegler-Natta catalyst formulation was preparedusing the following steps. In step one, a solution of triethylaluminumand dibutylmagnesium ((triethylaluminum)/(dibutylmagnesium) molar ratioof 20) was combined with a solution of tertiary butyl chloride andallowed to react for about 30 seconds (HUT-1); in step two, a solutionof titanium tetrachloride was added to the mixture formed in step oneand allowed to react for about 14 seconds (HUT-2), and; in step three,the mixture formed in step two was allowed to reactor for an additional3 seconds (HUT-3) prior to injection into R2. The in-line Ziegler-Nattaprocatalyst formulation was injected into R2 using process solvent, theflow rate of the catalyst containing solvent was about 49 kg/hr. Thein-line Ziegler-Natta catalyst formulation was formed in R2 by injectinga solution of diethyl aluminum ethoxide into R2. The quantity oftitanium tetrachloride “R2 (vii) (ppm)” added to reactor 2 (R2) is shownin Table 2A; to be clear in Example 62 the solution in R2 contained 6.21ppm of TiCl₄. The mole ratios of the in-line Ziegler-Natta catalystcomponents are also shown in Table 2A, specifically: R2 (vi)/(v) moleratio, i.e., [(tertiary butyl chloride)/(butyl ethyl magnesium)]; R2(viii)/(vii) mole ratio, i.e., [(diethyl aluminum ethoxide)/(titaniumtetrachloride)], and; R2 (ix)/(vii) mole ratio, i.e., [(triethylaluminum)/(titanium tetrachloride)]. To be clear, in Example 62, thefollowing mole ratios were used to synthesize the in-line Ziegler-Nattacatalyst: R2 (vi)/(v) mole ratio=1.78; R2 (viii)/(vii) mole ratio=1.35,and; R2 (ix)/(vii) mole ratio=0.35. In all of the Examples disclosed,100% of the diethyl aluminum ethoxide was injected directly into R2.

In Example 62 (single-site catalyst formulation in R1+in-lineZiegler-Natta catalyst in R2) the ethylene interpolymer product wasproduced at a production rate of 100.1 kg/h; in contrast, in ComparativeExample 15 (single-site catalyst formulation in both R1 and R2) themaximum production rate of the comparative ethylene interpolymer productwas 84.9 kg/h.

Average residence time of the solvent in a reactor is primarilyinfluenced by the amount of solvent flowing through each reactor and thetotal amount of solvent flowing through the solution process, thefollowing are representative or typical values for the examples shown inTables 2A-2C: average reactor residence times were: about 61 seconds inR1, about 73 seconds in R2 and about 50 seconds in R3 (the volume of R3was about 4.8 gallons (18 L)).

Polymerization in the continuous solution polymerization process wasterminated by adding a catalyst deactivator to the third exit streamexiting the tubular reactor (R3). The catalyst deactivator used wasoctanoic acid (caprylic acid), commercially available from P&GChemicals, Cincinnati, Ohio, U.S.A. The catalyst deactivator was addedsuch that the moles of fatty acid added were 50% of the total molaramount of titanium and aluminum added to the polymerization process; tobe clear, the moles of octanoic acid added=0.5×(moles titanium+molesaluminum); this mole ratio was consistently used in all examples.

A two-stage devolitizing process was employed to recover the ethyleneinterpolymer product from the process solvent, i.e., two vapor/liquidseparators were used and the second bottom stream (from the second V/Lseparator) was passed through a gear pump/pelletizer combination. DHT-4V(hydrotalcite), supplied by Kyowa Chemical Industry Co. LTD, Tokyo,Japan was used as a passivator, or acid scavenger, in the continuoussolution process. A slurry of DHT-4V in process solvent was added priorto the first V/L separator. The molar amount of DHT-4V added was about10-fold higher than the molar amount of chlorides added to the process;the chlorides added were titanium tetrachloride and tertiary butylchloride.

Prior to pelletization the ethylene interpolymer product was stabilizedby adding about 500 ppm of Irganox 1076 (a primary antioxidant) andabout 500 ppm of Irgafos 168 (a secondary antioxidant), based on weightof the ethylene interpolymer product. Antioxidants were dissolved inprocess solvent and added between the first and second V/L separators.

Tables 2B and 2C disclose additional solution process parameters, e.g.,ethylene and 1-octene splits between the reactors, reactor temperaturesand ethylene conversions, etc. recorded during the production of Example62 and Comparative Example 15. In Tables 2A-2C the targeted ethyleneinterpolymer product was 3.5 melt index (I₂) (ASTM D1239, 2.16 kg load,190° C.) and 0.941 g/cc (ASTM D792). In Comparative Example 15, thesingle-site catalyst formulation was injected into both reactor R1 andreactor R2 and ES^(R1) was 30%. In Example 62, the single site catalystformulation was injected into R1, the in-line Ziegler-Natta catalystformulation was injected into R2 and ESR¹ was 30%.

Tables 2B and 2C disclose additional solution process parameters, e.g.,ethylene and 1-octene splits between the reactors, reactor temperaturesand ethylene conversions, etc. recorded during the production of Example62 and Comparative Example 15. In Tables 2A-2C the targeted ethyleneinterpolymer product was 3.5 melt index (I₂) (ASTM D1239, 2.16 kg load,190° C.) and 0.941 g/cc (ASTM D792). In Comparative Example 15, thesingle-site catalyst formulation was injected into both reactor R1 andreactor R2 and ES^(R1) was 30%. In Example 62, the single site catalystformulation was injected into R1, the in-line Ziegler-Natta catalystformulation was injected into R2 and ES^(R1) was 30%.

Table 8 discloses two additional examples of interpolymer products(Example 71 and Example 73) suitable for rotomolding applications havingtarget melt index and density of about 2.0 dg/min and 0.948 g/cm³,respectively, and; Comparative Examples 16, 40 and 41 have similar meltindex and density. The data disclosed in Table 8 was generated on thesame continuous solution pilot plant (described above) employingessentially the same procedures, with the exception of adjusting processconditions to achieve the desired melt index and density. Example 71 and73 were produced using the catalyst PIC-1 (Cp[(t-Bu)₃PN]TiCl₂) in R1 andthe in-line Ziegler-Natta catalyst formulation in R2 (described above).In contrast, Comparative Examples 16, 40 and 41 were produced using thecatalyst PIC-1 in both R1 and R2. Prior to pelletization the products(Example 71 and 73, and; Comparative Examples 16, 40 and 41) werestabilized by adding about 500 ppm of Irgafos 168 (a secondaryantioxidant), based on weight of the ethylene interpolymer product; theantioxidant was dissolved in process solvent and added between the firstand second V/L separators. Table 9 discloses selected physicalproperties of Example 71 and 73, and; Comparative Examples 16, 40 and41.

Ethylene Interpolymer Product Compounding

A UV (ultra violet) light protective additive was compounded into theethylene interpolymer product using a twin screw compounding line.Ethylene interpolymer product (97.7 wt %) was tumble blended with anethylene interpolymer masterbatch (2.3 wt %) containing Tinuvin 622 (aUV-light stabilizer available from BASF Corporation, Florham Park, N.J.,U.S.A); this salt and pepper dry blend was melt mixed using a CoperionZSK26MC intermeshing co-rotating twin screw extruder with a screwdiameter of 26 mm and a length (L) to diameter (D) ratio of 32/1 (L/D).The extruder was operated at about 200° C. at a screw speed of about 200rpm and pelletized at a rate of about 20 kg/hr. The compounded ethyleneinterpolymer product contain about 1500 ppm of UV-stabilizer. Prior torotomolding, the compounded resin was passed through a grinder such thata powder of ethylene interpolymer product was produced having 35 US meshsize (mesh opening of 0.0197 inch (500 μm)).

Rotomolding

The powdered ethylene interpolymer products of this disclosure areconverted into rotomolded parts employing a rotational molding machine;specifically, a Rotospeed RS3-160 available from Ferry Industries Inc.(Stow, Ohio, USA). The Rotospeed has two arms which rotate about acentral axis within an enclosed oven. The arms are fitted with plateswhich rotate on an axis that is roughly perpendicular to the axis ofrotation of the arm. Each arm is fitted with six cast aluminum moldsthat produce a hollow rotomolded part of cubical shape, i.e.: 12.5inches (31.8 cm)×12.5 inches×12.5 inches. The arm rotation was set toabout 8 revolutions per minute (rpm) and the plate rotation was set toabout 2 rpm. Rotomolded parts having a nominal thickness of about 0.25inches (0.64 cm) were produced employing a standard charge of about 3.7kg of polyethylene resin in powder form; where the powder has a 35 USmesh size (mesh opening of 0.0197 inch (500 μm)). The temperature withinthe enclosed oven was maintained at a temperature of 560° F. (293° C.).The molds and their contents were heated in the oven for 20, 22 or 24minutes (see Table 12) to ensure that full powder densification wasachieved. The molds were subsequently cooled using air fans for about 30minutes prior to removing the part from the mold. Specimens werecollected from the molded parts for density, color and ARM Impacttesting. Typically, the density of the rotomolded part and rotomoldedtest specimens was slightly higher than the density of the ethyleneinterpolymer product that was produced in the pilot plant.

TABLE 1 Computer generated Simulated Example 13: single-site catalystformulation in R1 (PIC-1) and an in-line Ziegler-Natta catalystformulation in R2 and R3. Reactor 1 Reactor 2 Reactor 3 (R1) First (R2)Second (R3) Third Ethylene Ethylene Ethylene Simulated SimulatedPhysical Property Interpolymer Interpolymer Interpolymer Example 13Weight Percent (%) 36.2 56.3 7.5 100 M_(n) 63806 25653 20520 31963 M_(w)129354 84516 67281 99434 M_(z) 195677 198218 162400 195074Polydispersity (M_(w)/M_(n)) 2.03 3.29 3.28 3.11 Branch Frequency 12.611.4 15.6 12.1 (C₆ Branches per 1000 C.) CDBI₅₀ (%) (range) 90 to 95 55to 60 45 to 55 65 to 70 Density (g/cm³) 0.9087 0.9206 0.9154 0.9169 MeltIndex (dg/min) 0.31 1.92 4.7 1.0

TABLE 2A Continuous solution polymerization process data for Examples 62and Comparative Example 15. Comparative Sample Code Example 62 Example15 R1 Catalyst PIC-1 PIC-1 R2 Catalyst ZN PIC-1 R1 (i) (ppm) 0.20 0.14R1 (ii)/(i) mole ratio 100.0 65 R1 (iv)/(ii) mole ratio 0.00 0.3 R1(iii)/(i) mole ratio 1.10 1.1 R2 (i) (ppm) 0 0.3 R2 (ii)/(i) mole ratio0 25 R2 (iv)/(ii) mole ratio 0 0.3 R2 (iii)/(i) mole ratio 0 1.5 R2(vii) (ppm) 6.21 0 R2 (vi)/(v) mole ratio 1.78 0 R2 (viii)/(vii) moleratio 1.35 0 R2 (ix)/(vii) mole ratio 0.35 0 Prod. Rate (kg/h) 95.2 84.9

TABLE 2B Additional solution process parameters for Examples 62 andComparative Example 15. Comparative Sample Code Example 62 Example 15 R3volume (L) 18 18 ES^(R1) (%) 30 30 ES^(R2) (%) 70 70 ES^(R3) (%) 0 0 R1ethylene concentration 8.50 8.9 (wt %) R2 ethylene concentration 16.615.3 (wt %) R3 ethylene concentration 16.6 15.3 (wt %)((octene)/(ethylene)) in R1 0.083 0.055 (wt %) OS^(R1) (%) 100 100OS^(R2) (%) 0 0 OS^(R3) (%) 0 0 H₂ ^(R1) (ppm) 1.40 1.22 H₂ ^(R2) (ppm)14.49 2.00 H₂ ^(R3) (ppm) 0 0 Prod. Rate (kg/h) 95.2 84.9

TABLE 2C Additional solution process parameters for Examples 62 andComparative Example 15. Comparative Sample Code Example 62 Example15 R1total solution rate 355.9 309.8 (kg/h) R2 total solution rate 244.1290.2 (kg/h) R3 solution rate (kg/h) 0 0 Overall total solution rate600.0 600 (kg/h) R1 inlet temp (° C.) 30 30 R2 inlet temp (° C.) 30 30R3 inlet temp(° C.) 130 130 R1 Mean temp (° C.) 140.1 140.1 R2 Mean temp(° C.) 223.0 210.1 R3 exit temp (actual) (° C.) 230.2 210.3 R3 exit temp(calc) (° C.) 234.6 212.2 Q^(R1) (%) 91.7 91.7 Q^(R2) (%) 81.6 83.8Q^(R2+R3) (%) 91.0 87.8 Q^(R3) (%) 51.0 24.7 Q^(T) (%) 93.5 91.2 Prod.Rate (kg/h) 100.1 84.9 ^(a) R3 NIR probe fouled, Q^(R3) assumed to be55%

TABLE 3 Physical properties of Example 62 and Comparative Example 15produced in the a continuous solution process pilot plant. ComparativeSample Code Example 62 Example 15 Density (g/cc) 0.9426 0.9401 MeltIndex I₂ (dg/min) 3.50 2.76 Melt Flow Ratio (I₂₁/I₂) 25.4 24.8 StressExponent 1.26 1.28 Branch Freq/1000 C. 3.1 3.1 Comonomer (mole %) 0.60.6 M_(n) 26677 37412 M_(w) 74373 80572 M_(z) 160124 164797 M_(w)/M_(n)2.79 2.15 M_(z)/M_(w) 2.15 2.05

TABLE 4 Physical properties of Example 62, Comparative Example 15 andComparative O. Comparative Sample Code Example 62 Example 15 ComparativeO Density (g/cm³) 0.9436^(a) 0.9420^(a) 0.9406 Melt Index I₂ (dg/min)3.50 2.76 3.76 Internal Unsat/100 C. 0.002 0.018 0.016 Side Chain 0.0020.001 0.001 Unsat/100 C. Terminal Unsat/100 C. 0.052 0.01 0.008 Ti (ppm)9.2 0.35^(b) 0.35 Mg (ppm) 140 n/a n/a Cl (ppm) 284 n/a n/a Al (ppm) 127n/a n/a Plaque ESCR B10 40 37 45 (hr) (plaque sample) c2% FlexuralSecant 858 834 735 Modulus (MPa) ^(d)Elong. at Yield (%) 10 11 12^(d)Yield Strength (MPa) 22 22.2 21.7 ^(d)Ultimate Elong. (%) 970 1034973 ^(d)Ultimate Strength 36.2 35 33.6 (MPa) ^(d)Sec Mod 1% (MPa) 13031237 1078 ^(d)Sec Mod 2% (MPa) 825 795 740 Hexane Extractables 0.08 0.040.20 (%) (plaque sample) ^(a)density measured after additive compounding^(b)average: database on Ti (ppm) in SURPASS ® products (NOVA Chemicals)cFlexural properties, ASTM D790-10 ^(d)Tensile properties, ASTM D882-12

TABLE 5 Dilution Index (Y_(d)) and Dimensionless Modulus Data (X_(d))for selected embodiments of ethylene interpolymers of this disclosure(Examples), relative to Comparative S, A, D and E. (MFR = melt flow rate(I₂₁/I₂); MS = melt strength) Density MI MS η₀ G⁰ _(N) G*_(c) δ_(c)Sample Code [g/cm³] [dg/min] MFR [cN] [kPa · s] [MPa] [kPa] [°] X_(d)Y_(d) Comp. S 0.9176 0.86 29.2 6.46 11.5 1.50 9.43 74.0 0.00 0.02 Comp.A 0.9199 0.96 29.6 5.99 10.6 1.17 5.89 80.1 −0.20 3.66 Example 6 0.91520.67 23.7 7.05 12.9 1.57 7.89 79.6 −0.08 4.69 Example 71 0.9472 1.8 33.1n/a 6.37 0.105 6.50 75.3 −0.16 −0.68 Example 73 0.9476 1.5 30.4 n/a 7.450.119 7.35 74.7 −0.11 −0.61 Example 101 0.9173 0.95 26.3 5.73 9.67 0.847.64 79.0 −0.09 3.93 Example 102 0.9176 0.97 22.6 5.65 9.38 1.46 7.4679.5 −0.10 4.29 Example 103 0.9172 0.96 25.3 5.68 9.38 1.44 7.81 79.3−0.08 4.29 Example 110 0.9252 0.98 23.9 5.57 9.41 1.64 8.90 78.1 −0.033.8 Example 115 0.9171 0.75 23.4 6.83 12.4 1.48 8.18 79.2 −0.06 4.44Example 200 0.9250 1.04 24.2 5.33 8.81 0.97 8.97 78.9 −0.02 4.65 Example201 0.9165 1.01 27.1 5.43 8.75 0.85 6.75 79.7 −0.15 3.91 Example 1200.9204 1.00 24.0 5.99 10.2 1.45 13.5 73.6 0.16 1.82 Example 130 0.92320.94 22.1 6.21 10.4 0.97 11.6 75.7 0.09 3.02 Example 131 0.9242 0.9522.1 6.24 10.7 1.02 11.6 75.3 0.09 2.59 Comp. Ex. 41 0.9483 2.0 32.1 n/a5.19 0.124 7.40 75.3 −0.11 0.02 Comp. D 0.9204 0.82 30.6 7.61 15.4 1.5810.8 70.4 0.06 −2.77 Comp. E 0.9161 1.00 30.5 7.06 13.8 1.42 10.4 70.50.04 −2.91

TABLE 6A Unsaturation data of several embodiments of the disclosedethylene interpolymers, as well as Comparative B, C, E, E2, G, H, H2, Iand J; as determined by ASTM D3124-98 and ASTM D6248-98. Density MeltIndex Melt Flow Stress Unsaturations per 100 C. Sample Code (g/cm³) I₂(dg/min) Ratio (I₂₁/I₂) Exponent Internal Side Chain Terminal Example 110.9113 0.91 24.8 1.24 0.009 0.004 0.037 Example 6 0.9152 0.67 23.7 1.230.008 0.004 0.038 Example 4 0.9154 0.97 37.1 1.33 0.009 0.004 0.047Example 7 0.9155 0.70 25.7 1.24 0.008 0.005 0.042 Example 2 0.9160 1.0427.0 1.26 0.009 0.005 0.048 Example 5 0.9163 1.04 25.9 1.23 0.008 0.0050.042 Example 3 0.9164 0.9 29.2 1.27 0.009 0.004 0.049 Example 53 0.91640.9 29.2 1.27 0.009 0.004 0.049 Example 51 0.9165 1.01 28.0 1.26 0.0090.003 0.049 Example 201 0.9165 1.01 27.1 1.22 0.008 0.007 0.048 Example1 0.9169 0.88 23.4 1.23 0.008 0.005 0.044 Example 52 0.9169 0.85 29.41.28 0.008 0.002 0.049 Example 55 0.9170 0.91 29.8 1.29 0.009 0.0040.050 Example 115 0.9171 0.75 23.4 1.22 0.007 0.003 0.041 Example 430.9174 1.08 24.2 1.23 0.007 0.007 0.046 Comparative E2 0.9138 1.56 24.11.26 0.006 0.007 0.019 Comparative E 0.9144 1.49 25.6 1.29 0.004 0.0050.024 Comparative J 0.9151 4.2 21.8 1.2 0.006 0.002 0.024 Comparative C0.9161 1 30.5 1.35 0.004 0.004 0.030 Comparative B 0.9179 1.01 30.2 1.330.004 0.002 0.025 Comparative H2 0.9189 0.89 30.6 1.36 0.004 0.002 0.021Comparative H 0.9191 0.9 29.6 1.34 0.004 0.003 0.020 Comparative I0.9415 0.87 62 1.61 0.002 0.000 0.025 Comparative G 0.9612 0.89 49 1.580.000 0.000 0.023

TABLE 6B Additional unsaturation data of several embodiments of thedisclosed ethylene interpolymers; as determined by ASTM D3124-98 andASTM D6248-98 Density Melt Index Melt Flow Unsaturations per 100 C.Sample Code (g/cm³) I₂ (dg/min) Ratio (I₂₁/I₂) S. Ex. Internal SideChain Terminal Example 8 0.9176 4.64 27.2 1.25 0.009 0.001 0.048 Example42 0.9176 0.99 23.9 1.23 0.007 0.006 0.046 Example 102 0.9176 0.97 22.61.24 0.007 0.005 0.044 Example 54 0.9176 0.94 29.9 1.29 0.009 0.0020.049 Example 41 0.9178 0.93 23.8 1.23 0.007 0.006 0.046 Example 440.9179 0.93 23.4 1.23 0.007 0.007 0.045 Example 9 0.9190 0.91 40.3 1.380.008 0.003 0.052 Example 200 0.9250 1.04 24.2 1.24 0.006 0.005 0.050Example 60 0.9381 4.57 22.2 1.23 0.005 0.002 0.053 Example 61 0.93964.82 20.2 1.23 0.002 0.002 0.053 Example 62 0.9426 3.5 25.4 1.26 0.0020.002 0.052 Example 70 0.9468 1.9 32.3 1.34 0.001 0.002 0.042 Example 710.9470 1.61 34.8 1.35 0.001 0.001 0.048 Example 72 0.9471 1.51 31.4 1.340.001 0.002 0.043 Example 73 0.9472 1.51 31.6 1.35 0.001 0.002 0.047Example 80 0.9528 1.53 41.1 1.38 0.002 0.000 0.035 Example 81 0.95331.61 50 1.43 0.002 0.000 0.044 Example 82 0.9546 1.6 59.6 1.5 0.0010.000 0.045 Example 90 0.9588 7.51 29 1.28 0.001 0.000 0.042 Example 910.9589 6.72 30.4 1.29 0.002 0.000 0.041 Example 20 0.9596 1.21 31.3 1.350.002 0.001 0.036 Example 21 0.9618 1.31 38.3 1.39 0.002 0.001 0.037Example 22 0.9620 1.3 51 1.49 0.002 0.001 0.041 Example 23 0.9621 0.6378.9 1.68 0.002 0.001 0.042 Example 24 0.9646 1.98 83 1.79 0.001 0.0010.052

TABLE 7A Neutron Activation Analysis (NAA) catalyst residues in severalembodiments of the disclosed ethylene interpolymers, as well asComparatives G, I, J, B, C, E, E2, H and H2. N.A.A. Elemental SampleDensity Melt Index Analysis (ppm) Code (g/cm³) I₂ (dg/min) Ti Mg Cl AlExample 60 0.9381 4.57 9.0 140 284 127 Example 62 0.9426 3.50 9.2 179358 94 Example 70 0.9468 1.90 6.2 148 299 99 Example 71 0.9470 1.61 6.8168 348 87 Example 72 0.9471 1.51 5.8 178 365 88 Example 73 0.9472 1.517.2 142 281 66 Example 80 0.9528 1.53 4.3 141 288 82 Example 81 0.95331.61 6.4 163 332 82 Example 82 0.9546 1.60 5.8 132 250 95 Example 900.9588 7.51 6.7 143 286 94 Example 91 0.9589 6.72 6.7 231 85 112 Example1 0.9169 0.88 6.1 199 99 97 Example 2 0.9160 1.04 7.4 229 104 112Example 3 0.9164 0.90 7.3 268 137 129 Comparative G 0.9612 0.89 1.6 17.253 11 Comparative I 0.9415 0.87 2.3 102 24 53 Comparative J 0.9151 4.201.4 <2 0.6 7.9 Comparative B 0.9179 1.01 0.3 13.7 47 9.3 Comparative C0.9161 1.00 2.0 9.0 25 5.4 Comparative E2 0.9138 1.56 1.2 9.8 32.2 6.8Comparative E 0.9144 1.49 1.3 14.6 48.8 11.3 Comparative H 0.9191 0.902.2 14.6 48.8 11.3 Comparative H2 0.9189 0.89 2.2 253 122 130

TABLE 7B Additional Neutron Activation Analysis (NAA) catalyst residuesin several embodiments of the disclosed ethylene interpolymers. DensityMelt Index N.A.A. Elemental Analysis (ppm) Sample Code (g/cm³) I₂(dg/min) Ti Mg Cl Al Example 4 0.9154 0.97 9.6 287 45 140 Example 50.9163 1.04 6.7 261 70 131 Example 6 0.9152 0.67 5.2 245 48 119 Example7 0.9155 0.70 7.7 365 102 177 Example 8 0.9176 4.64 7.6 234 86 117Example 9 0.9190 0.91 6.4 199 78 99 Example 51 0.9165 1.01 5.9 207 73106 Example 52 0.9169 0.85 5.2 229 104 112 Example 53 0.9164 0.90 7.3347 101 167 Example 54 0.9176 0.94 7.5 295 100 146 Example 55 0.91700.91 7.1 189 101 90 Example 41 0.9178 0.93 7.2 199 103 92 Example 420.9176 0.99 7.5 188 104 86 Example 43 0.9174 1.08 7.4 192 101 91 Example44 0.9179 0.93 7.2 230 121 110 Example 102 0.9176 0.97 9.5 239 60 117Example 115 0.9171 0.75 5.1 258 115 130 Example 61 0.9396 4.82 8.3 35296 179 Example 10 0.9168 0.94 7.8 333 91 170 Example 120 0.9204 1.00 7.3284 75 149 Example 130 0.9232 0.94 5.8 292 114 147 Example 131 0.92420.95 8.6 81.4 173 94 Example 200 0.9250 1.04 6.3 90.1 190 104

TABLE 8 Continuous solution polymerization process data for Examples 71and 73; relative to Comparative Examples 16, 40 and 41; target meltindex of about 2.0 dg/min and target density of about 0.948 g/cm³. Comp.Comp. Comp. Ex. 73 Ex. 71 Ex. 16 Ex. 40 Ex. 41 R1 Catalyst PIC-1 PIC-1PIC-1 PIC-1 PIC-1 R2 Catalyst ZN ZN PIC-1 PIC-1 PIC-1 R1 (i) (ppm) 0.150.13 0.10 0.10 0.10 R2 (i) (ppm) 0 0 0.35 0.22 0.38 R2 (vii) (ppm) 4.34.9 0 0 0 ES^(R1) (%) 30 35 35 35 35 ES^(R2) (%) 70 65 65 65 65 ES^(R3)(%) 0 0 0 0 0 ((octene)/(ethylene)) 0.043 0.052 0.035 0.021 0.028 in R1(wt %) OS^(R1) (%) 100 100 100 100 100 OS^(R2) (%) 0 0 0 0 0 OS^(R3) (%)0 0 0 0 0 H₂ ^(R1) (ppm) 0.9 1.2 1.0 0.8 1.2 H₂ ^(R2) (ppm) 24.0 34.03.3 4.5 6.0 H₂ ^(R3) (ppm) 0 0 0 0 0 R1 Mean temp (° C.) 140 135 139 143144 R2 Mean temp (° C.) 217 217 210 208 211

TABLE 9 Physical properties of Example 71 and 73; relative toComparative Example Ex. 16, Comparative Example 40 and ComparativeExample 41. Comp. Comp. Comp. Sample Code Ex. 73 Ex. 71 Ex. 16 Ex. 40Ex. 41 Density (g/cm³) 0.9476 0.9472 0.9454 0.9480 0.9483 Melt Index I₂(dg/min) 1.5 1.8 1.4 1.2 2.0 Melt Flow Ratio I₂₁/I₂ (dg/min) 30.4 33.134.1 32.4 32.1 Stress Exponent 1.33 1.33 1.37 1.36 1.34 Branch Freq/1000C. 2.0 2.0 1.9 1.2 1.9 Comonomer (mole %) 0.40 0.40 0.40 0.20 0.40 M_(n)26,026 26,051 34,623 35,000 27,000 M_(w) 100,009 94,966 96,628 102,00086,000 M_(z) 274,043 265,760 247,553 264,000 221,500 M_(w)/M_(n) 3.843.65 2.79 2.91 3.19 M_(z)/M_(w) 2.74 2.80 2.56 2.59 2.58 CDBI₅₀ 80.283.2 90.2 n/a n/a TREF Elution Temp. (° C.), peak 96.7 95.9 95.2 n/a n/aInternal Unsat/100 C. 0.001 0.001 0.015 n/a n/a Side Chain Unsat/100 C.0.002 0.001 0.000 n/a n/a Terminal Unsat/100 C. 0.047 0.048 0.0090.0093^(a) 0.0093^(a) Ti (ppm) 7.2 6.8 0.35^(b) 0.35^(b) 0.35^(b)^(a)average: database on Terminal Unsaturation/100 C. in SURPASS ®products (NOVA Chemicals) ^(b)average: database on Ti (ppm) in SURPASS ®products (NOVA Chemicals)

TABLE 10 GPC deconvolution results, Example 71 and Example 73; relativeto Comparative Examples 16, 40 and 41. Comp. Comp. Comp. Sample Code Ex.73 Ex. 71 Ex. 16 Ex. 40 Ex. 41 Density (g/cm³) 0.9476 0.9472 0.94540.9480 0.9483 Melt Index I₂ (dg/min) 1.5 1.8 1.4 1.2 2.0 M_(n) (1^(st)ethylene interpolymer) 88135 84954 102051 111254 83511 M_(w) (1^(st)ethylene interpolymer) 181539 174406 204103 222507 167023 M_(w)/M_(n)(1^(st) ethylene interpolymer) 2.06 2.05 2.00 2.00 2.00 Weight Fraction0.309 0.356 0.296 0.289 0.333 (1^(st) ethylene interpolymer) M_(n)(2^(nd) ethylene interpolymer) 18966 17632 22364 23664 19705 M_(w)(2^(nd) ethylene interpolymer) 52488 45181 44727 47328 39410 M_(w)/M_(n)(2^(nd) ethylene interpolymer) 2.77 2.56 2.00 2.00 2.00 Weight Fraction0.605 0.565 0.704 0.711 0.667 (2^(st) ethylene interpolymer) M_(n)(3^(rd) ethylene interpolymer) 16070 14796 M_(w) (3^(rd) ethyleneinterpolymer) 40436 34705 M_(w)/M_(n) (3^(rd) ethylene interpolymer)2.52 2.35 Weight Fraction 0.085 0.079 (3^(rd) ethylene interpolymer)

TABLE 11 Compression molded plaque physical properties of Example 71 andExample 73; relative to Comparative Examples 16, 40 and 41. All samplescontained a UV additive. Comp. Comp. Comp. Sample Code Ex. 73 Ex. 71 Ex.16 Ex. 40 Ex. 41 Flex Secant Mod. 1191 ± 1154 ± 1098 ± 1202 ± 1057 ± 1%(MPa) 12 12 16 24 25 ESCR Cond. A100 >1000 >1000 544 120  80 (hr) 100%CO-630 ESCR Cond. B100 >1000 >1000 858 112 141 (hr) 100% CO-630

TABLE 12 Low temperature (−40° C.) ARM impact properties of rotomoldedparts prepared from Example 71 and Example 73; relative to ComparativeExamples 16, 40 and 41. All samples contained a UV additive. Sample CodeEx. 73 Ex. 71 Comp. Ex. 16 Comp. Ex. 40 Comp. Ex. 41 Oven 22 24 22 20 2220 22 22 24 Residence Time (min) ARM Mean 138 176 158 158 160 130 185185 202 Failure Energy (ft.lb) ARM 90 70 100 100 50 100 92 100 100Ductility (%) Density 0.946 0.949 0.946 0.946 0.947 0.947 0.952 0.9490.950 (g/cm³)

We claim:
 1. A rotomolded article comprising a wall structure; whereinsaid wall structure comprises at least one layer comprising an ethyleneinterpolymer product comprising: (i) a first ethylene interpolymer; (ii)a second ethylene interpolymer, and; (iii) optionally a third ethyleneinterpolymer; wherein said ethylene interpolymer product has a DilutionIndex, Y_(d), greater than −1.0.
 2. The rotomolded article of claim 1,further characterized as having ≧0.03 terminal vinyl unsaturations per100 carbon atoms.
 3. The rotomolded article of claim 1, furthercharacterized as having ≧3 parts per million (ppm) of a total catalyticmetal.
 4. The rotomolded article of claim 1, further characterized ashaving ≧0.03 terminal vinyl unsaturations per 100 carbons and ≧3 partsper million (ppm) of total catalytic metal.
 5. The rotomolded article ofclaim 1 having a melt index from about 0.5 to about 15 dg/minute;wherein melt index is measured according to ASTM D1238 (2.16 kg load and190° C.).
 6. The rotomolded article of claim 1 having a density fromabout 0.930 to about 0.955 g/cc; wherein density is measured accordingto ASTM D792.
 7. The rotomolded article of claim 1 having a M_(w)/M_(n)from about 2 to about
 6. 8. The rotomolded article of claim 1 having aCDBI₅₀ from about 50% to about 98%.
 9. The rotomolded article of claim1; wherein (i) said first ethylene interpolymer is from about 15 toabout 60 weight percent of said ethylene interpolymer product; (ii) saidsecond ethylene interpolymer is from about 30 to about 85 weight percentof said ethylene interpolymer product, and; (iii) optionally said thirdethylene interpolymer is from about 0 to about 30 weight percent of saidethylene interpolymer product; wherein weight percent is the weight ofsaid first, said second or said optional third ethylene interpolymerdivided by the weight of said ethylene interpolymer product.
 10. Therotomolded article of claim 1; wherein (i) said first ethyleneinterpolymer has a melt index from about 0.01 to about 200 dg/minute;(ii) said second ethylene interpolymer has melt index from about 0.3 toabout 1000 dg/minute, and; (iii) optionally said third ethyleneinterpolymer has a melt index from about 0.5 to about 2000 dg/minute;wherein melt index is measured according to ASTM D1238 (2.16 kg load and190° C.).
 11. The rotomolded article of claim 1; wherein (i) said firstethylene interpolymer has a density from about 0.855 g/cm³ to about0.975 g/cc; (ii) said second ethylene interpolymer has a density fromabout 0.89 g/cm³ to about 0.975 g/cc, and; (iii) optionally said thirdethylene interpolymer has density from about 0.89 to about 0.975 g/cc;wherein density is measured according to ASTM D792.
 12. The rotomoldedarticle of claim 1; wherein said ethylene interpolymer product issynthesized using a solution polymerization process.
 13. The rotomoldedarticle of claim 1 further comprising from 0.1 to about 2.0 mole percentof one or more α-olefin.
 14. The rotomolded article of claim 13; whereinsaid one or more α-olefin are C₃ to C₁₀ α-olefins.
 15. The rotomoldedarticle of claim 13; wherein said one or more α-olefin is 1-hexene,1-octene or a mixture of 1-hexene and 1-octene.
 16. The rotomoldedarticle of claim 1; wherein said first ethylene interpolymer issynthesized using a single-site catalyst formulation.
 17. The rotomoldedarticle of claim 1; wherein said second ethylene interpolymer issynthesized using a first heterogeneous catalyst formulation.
 18. Therotomolded article of claim 1; wherein said third ethylene interpolymeris synthesized using a first heterogeneous catalyst formulation or asecond heterogeneous catalyst formulation.
 19. The rotomolded article ofclaim 1 wherein said second ethylene interpolymer is synthesized using afirst in-line Ziegler Natta catalyst formulation or a first batchZiegler-Natta catalyst formulation; optionally, said third ethyleneinterpolymer is synthesized using said first in-line Ziegler Nattacatalyst formulation or said first batch Ziegler-Natta catalystformulation.
 20. The rotomolded article of claim 1 wherein said thirdethylene interpolymer is synthesized using a second in-line ZieglerNatta catalyst formulation or a second batch Ziegler-Natta catalystformulation.
 21. The rotomolded article of claim 1, having ≦1 part permillion (ppm) of a metal A; wherein said metal A originates from asingle site catalyst formulation used to synthesize said first ethyleneinterpolymer.
 22. The rotomolded article of claim 21; wherein said metalA is titanium, zirconium or hafnium.
 23. The rotomolded article of claim1 having a metal B and optionally a metal C and the total amount of saidmetal B plus said metal C is from about 3 to about 11 parts per million;wherein said metal B originates from a first heterogeneous catalystformulation used to synthesize said second ethylene interpolymer andoptionally said metal C originates from a second heterogeneous catalystformulation used to synthesize said third ethylene interpolymer;optionally said metal B and said metal C are the same metal.
 24. Therotomolded article of claim 23; wherein said metal B and said metal C,are independently selected from titanium, zirconium, hafnium, vanadium,niobium, tantalum, chromium, molybdenum, tungsten, manganese,technetium, rhenium, iron, ruthenium or osmium.
 25. The rotomoldedarticle of claim 23; wherein said metal B and said metal C, areindependently selected from titanium, zirconium, hafnium, vanadium orchromium.
 26. The rotomolded article of claim 1 wherein said firstethylene interpolymer has a first M_(w)/M_(n), said second ethyleneinterpolymer has a second M_(w)/M_(n) and said optional third ethyleneinterpolymer has a third M_(w)/M_(n); wherein said first M_(w)/M_(n) islower than said second M_(w)/M_(n) and said optional third M_(w)/M_(n).27. The rotomolded article of claim 26; wherein the blending of saidsecond ethylene interpolymer and said third ethylene interpolymer formsa heterogeneous ethylene interpolymer blend having a fourth M_(w)/M_(n);wherein said fourth M_(w)/M_(n) is not broader than said secondM_(w)/M_(n).
 28. The rotomolded article of claim 26 wherein said secondM_(w)/M_(n) and said optional third M_(w)/M_(n) are ≦4.0.
 29. Therotomolded article of claim 1; wherein said first ethylene interpolymerhas a first CDBI₅₀ from about 70 to about 98%, said second ethyleneinterpolymer has a second CDBI₅₀ from about 45 to about 98% and saidoptional third ethylene interpolymer has a third CDBI₅₀ from about 35 toabout 98%.
 30. The rotomolded article of claim 29; wherein said firstCDBI₅₀ is higher than said second CDBI₅₀; optionally said first CDBI₅₀is higher than said third CDBI₅₀.
 31. The rotomolded article of claim 1,wherein said wall structure: (i) has an ARM impact mean failure energyof ≧120 ft·lb; (ii) has an ARM impact ductility of ≧50%, and; (iii)passes an ESCR test Condition A100 and a comparative wall structurefails said ESCR test Condition A100; wherein said wall structurecomprising said ethylene interpolymer product comprises said firstethylene interpolymer synthesized using a single-site catalystformulation, said second ethylene interpolymer synthesized using a firstheterogeneous catalyst formulation and optionally said third ethyleneinterpolymer synthesized using said first heterogeneous catalystformulation or a second heterogeneous catalyst formulation; wherein saidcomparative wall structure has the same construction but said ethyleneinterpolymer product is replaced with a comparative ethyleneinterpolymer synthesized using one or more single-site catalystformulations; wherein, said ESCR test Condition A100 is passed if afailure time (F^(A) ₅₀) is ≧1000 hr or said ESCR test Condition A100 isfailed if said failure time (F^(A) ₅₀) is <1000 hr, wherein said failuretime (F^(A) ₅₀) is estimated graphically as described in Annex A1 ofASTM D1693, and; wherein said ARM impact mean failure energy and saidARM impact ductility are measured at −40° C. according to ASTM D5628.32. The rotomolded article of claim 1, wherein said wall structure: (i)has an ARM impact mean failure energy of ≧120 ft·lb; (ii) has an ARMimpact ductility of ≧50%, and; (iii) passes an ESCR test Condition B100and a comparative wall structure fails said ESCR test Condition B100;wherein said wall structure comprising said ethylene interpolymerproduct comprises said first ethylene interpolymer synthesized using asingle-site catalyst formulation, said second ethylene interpolymersynthesized using a first heterogeneous catalyst formulation andoptionally said third ethylene interpolymer synthesized using said firstor a second heterogeneous catalyst formulation; wherein said comparativewall structure has the same construction but said ethylene interpolymerproduct is replaced with a comparative ethylene interpolymer synthesizedusing one or more single-site catalyst formulations; wherein, said ESCRtest Condition B100 is passed if a failure time (F^(B) ₅₀) is ≧1000 hror said ESCR test Condition B100 is failed if said failure time (F^(B)₅₀) is <1000 hr, wherein said failure time (F^(B) ₅₀) is estimatedgraphically as described in Annex A1 of ASTM D1693, and; wherein saidARM impact mean failure energy and said ARM impact ductility aremeasured at −40° C. according to ASTM D5628.
 33. The rotomolded articleof claim 1, wherein said wall structure: (i) has an ARM impact meanfailure energy of ≧120 ft·lb; (ii) has an ARM impact ductility of ≧50%;(iii) passes an ESCR test Condition A100 and a comparative wallstructure fails said ESCR test Condition A100, and; (iv) passes an ESCRtest Condition B100 and a comparative wall structure fails said ESCRtest Condition B100; wherein said wall structure comprising saidethylene interpolymer product comprises said first ethylene interpolymersynthesized using a single-site catalyst formulation, said secondethylene interpolymer synthesized using a first heterogeneous catalystformulation and optionally said third ethylene interpolymer synthesizedusing said first heterogeneous catalyst formulation or a secondheterogeneous catalyst formulation; wherein said comparative wallstructure has the same construction but said ethylene interpolymerproduct is replaced with a comparative ethylene interpolymer synthesizedusing one or more single-site catalyst formulations; wherein, said ESCRtest Condition A100 is passed if a failure time (F^(A) ₅₀) is ≧1000 hror said ESCR test Condition A100 is failed if said failure time (F^(A)₅₀) is <1000 hr and said ESCR test Condition B100 is passed if a failuretime (F^(B) ₅₀) is ≧1000 hr or said ESCR test Condition B100 is failedif said failure time (F^(B) ₅₀) is <1000 hr, wherein said failure times(F^(A) ₅₀) and (F^(B) ₅₀) are estimated graphically as described inAnnex A1 of ASTM D1693, and; wherein said ARM impact mean failure energyand said ARM impact ductility are measured at −40° C. according to ASTMD5628.
 34. The rotomolded article of claim 2, wherein said wallstructure: (i) has an ARM impact mean failure energy of ≧120 ft·lb; (ii)has an ARM impact ductility of ≧50%, and; (iii) passes an ESCR testCondition A100 and a comparative wall structure fails said ESCR testCondition A100; wherein said wall structure comprising said ethyleneinterpolymer product comprises said first ethylene interpolymersynthesized using a single-site catalyst formulation, said secondethylene interpolymer synthesized using a first heterogeneous catalystformulation and optionally said third ethylene interpolymer synthesizedusing said first heterogeneous catalyst formulation a secondheterogeneous catalyst formulation; wherein said comparative wallstructure has the same construction but said ethylene interpolymerproduct is replaced with a comparative ethylene interpolymer synthesizedusing one or more single-site catalyst formulations; wherein, said ESCRtest Condition A100 is passed if a failure time (F^(A) ₅₀) is ≧1000 hror said ESCR test Condition A100 is failed if said failure time (F^(A)₅₀) is <1000 hr, wherein said failure time (F^(A) ₅₀) is estimatedgraphically as described in Annex A1 of ASTM D1693, and; wherein saidARM impact mean failure energy and said ARM impact ductility aremeasured at −40° C. according to ASTM D5628.
 35. The rotomolded articleof claim 2, wherein said wall structure: (i) has an ARM impact meanfailure energy of ≧120 ft·lb; (ii) has an ARM impact ductility of ≧50%,and; (iii) passes an ESCR test Condition B100 and a comparative wallstructure fails said ESCR test Condition B100; wherein said wallstructure comprising said ethylene interpolymer product comprises saidfirst ethylene interpolymer synthesized using a single-site catalystformulation, said second ethylene interpolymer synthesized using a firstheterogeneous catalyst formulation and optionally said third ethyleneinterpolymer synthesized using said first or a second heterogeneouscatalyst formulation; wherein said comparative wall structure has thesame construction but said ethylene interpolymer product is replacedwith a comparative ethylene interpolymer synthesized using one or moresingle-site catalyst formulations; wherein, said ESCR test ConditionB100 is passed if a failure time (F^(B) ₅₀) is ≧1000 hr or said ESCRtest Condition B100 is failed if said failure time (F^(B) ₅₀) is <1000hr, wherein said failure time (F³50) is estimated graphically asdescribed in Annex A1 of ASTM D1693, and; wherein said ARM impact meanfailure energy and said ARM impact ductility are measured at −40° C.according to ASTM D5628.
 36. The rotomolded article of claim 2, whereinsaid wall structure: (i) has an ARM impact mean failure energy of ≧120ft·lb; (ii) has an ARM impact ductility of ≧50%; (iii) passes an ESCRtest Condition A100 and a comparative wall structure fails said ESCRtest Condition A100, and; (iv) passes an ESCR test Condition B100 and acomparative wall structure fails said ESCR test Condition B100; whereinsaid wall structure comprising said ethylene interpolymer productcomprises said first ethylene interpolymer synthesized using asingle-site catalyst formulation, said second ethylene interpolymersynthesized using a first heterogeneous catalyst formulation andoptionally said third ethylene interpolymer synthesized using said firstheterogeneous catalyst formulation or a second heterogeneous catalystformulation; wherein said comparative wall structure has the sameconstruction but said ethylene interpolymer product is replaced with acomparative ethylene interpolymer synthesized using one or moresingle-site catalyst formulations; wherein, said ESCR test ConditionA100 is passed if a failure time (F^(A) ₅₀) is ≧1000 hr or said ESCRtest Condition A100 is failed if said failure time (F^(A) ₅₀) is <1000hr and said ESCR test Condition B100 is passed if a failure time (F^(B)₅₀) is ≧1000 hr or said ESCR test Condition B100 is failed if saidfailure time (F^(B) ₅₀) is <1000 hr, wherein said failure times (F^(A)₅₀) and (F^(B) ₅₀) are estimated graphically as described in Annex A1 ofASTM D1693, and; wherein said ARM impact mean failure energy and saidARM impact ductility are measured at −40° C. according to ASTM D5628.37. The rotomolded article of claim 3, wherein said wall structure: (i)has an ARM impact mean failure energy of ≧120 ft·lb; (ii) has an ARMimpact ductility of ≧50%, and; (iii) passes an ESCR test Condition A100and a comparative wall structure fails said ESCR test Condition A100;wherein said wall structure comprising said ethylene interpolymerproduct comprises said first ethylene interpolymer synthesized using asingle-site catalyst formulation, said second ethylene interpolymersynthesized using a first heterogeneous catalyst formulation andoptionally said third ethylene interpolymer synthesized using said firstheterogeneous catalyst formulation a second heterogeneous catalystformulation; wherein said comparative wall structure has the sameconstruction but said ethylene interpolymer product is replaced with acomparative ethylene interpolymer synthesized using one or moresingle-site catalyst formulations; wherein, said ESCR test ConditionA100 is passed if a failure time (F^(A) ₅₀) is ≧1000 hr or said ESCRtest Condition A100 is failed if said failure time (F^(A) ₅₀) is <1000hr, wherein said failure time (F^(A) ₅₀) is estimated graphically asdescribed in Annex A1 of ASTM D1693, and; wherein said ARM impact meanfailure energy and said ARM impact ductility are measured at −40° C.according to ASTM D5628.
 38. The rotomolded article of claim 3, whereinsaid wall structure: (i) has an ARM impact mean failure energy of ≧120ft·lb; (ii) has an ARM impact ductility of ≧50%, and; (iii) passes anESCR test Condition B100 and a comparative wall structure fails saidESCR test Condition B100; wherein said wall structure comprising saidethylene interpolymer product comprises said first ethylene interpolymersynthesized using a single-site catalyst formulation, said secondethylene interpolymer synthesized using a first heterogeneous catalystformulation and optionally said third ethylene interpolymer synthesizedusing said first or a second heterogeneous catalyst formulation; whereinsaid comparative wall structure has the same construction but saidethylene interpolymer product is replaced with a comparative ethyleneinterpolymer synthesized using one or more single-site catalystformulations; wherein, said ESCR test Condition B100 is passed if afailure time (F^(B) ₅₀) is ≧1000 hr or said ESCR test Condition B100 isfailed if said failure time (F^(B) ₅₀) is <1000 hr, wherein said failuretime (F^(B) ₅₀) is estimated graphically as described in Annex A1 ofASTM D1693, and; wherein said ARM impact mean failure energy and saidARM impact ductility are measured at −40° C. according to ASTM D5628.39. The rotomolded article of claim 3, wherein said wall structure: (i)has an ARM impact mean failure energy of ≧120 ft·lb; (ii) has an ARMimpact ductility of ≧50%; (iii) passes an ESCR test Condition A100 and acomparative wall structure fails said ESCR test Condition A100, and;(iv) passes an ESCR test Condition B100 and a comparative wall structurefails said ESCR test Condition B100; wherein said wall structurecomprising said ethylene interpolymer product comprises said firstethylene interpolymer synthesized using a single-site catalystformulation, said second ethylene interpolymer synthesized using a firstheterogeneous catalyst formulation and optionally said third ethyleneinterpolymer synthesized using said first heterogeneous catalystformulation or a second heterogeneous catalyst formulation; wherein saidcomparative wall structure has the same construction but said ethyleneinterpolymer product is replaced with a comparative ethyleneinterpolymer synthesized using one or more single-site catalystformulations; wherein, said ESCR test Condition A100 is passed if afailure time (F^(A) ₅₀) is ≧1000 hr or said ESCR test Condition A100 isfailed if said failure time (F^(A) ₅₀) is <1000 hr and said ESCR testCondition B100 is passed if a failure time (F^(B) ₅₀) is ≧1000 hr orsaid ESCR test Condition B100 is failed if said failure time (F^(B) ₅₀)is <1000 hr, wherein said failure times (F^(A) ₅₀) and (F^(B) ₅₀) areestimated graphically as described in Annex A1 of ASTM D1693, and;wherein said ARM impact mean failure energy and said ARM impactductility are measured at −40° C. according to ASTM D5628.
 40. Therotomolded article of claim 4, wherein said wall structure: (i) has anARM impact mean failure energy of ≧120 ft·lb; (ii) has an ARM impactductility of ≧50%, and; (iii) passes an ESCR test Condition A100 and acomparative wall structure fails said ESCR test Condition A100; whereinsaid wall structure comprising said ethylene interpolymer productcomprises said first ethylene interpolymer synthesized using asingle-site catalyst formulation, said second ethylene interpolymersynthesized using a first heterogeneous catalyst formulation andoptionally said third ethylene interpolymer synthesized using said firstheterogeneous catalyst formulation a second heterogeneous catalystformulation; wherein said comparative wall structure has the sameconstruction but said ethylene interpolymer product is replaced with acomparative ethylene interpolymer synthesized using one or moresingle-site catalyst formulations; wherein, said ESCR test ConditionA100 is passed if a failure time (F^(A) ₅₀) is ≧1000 hr or said ESCRtest Condition A100 is failed if said failure time (F^(A) ₅₀) is <1000hr, wherein said failure time (F^(A) ₅₀) is estimated graphically asdescribed in Annex A1 of ASTM D1693, and; wherein said ARM impact meanfailure energy and said ARM impact ductility are measured at −40° C.according to ASTM D5628.
 41. The rotomolded article of claim 4, whereinsaid wall structure: (i) has an ARM impact mean failure energy of ≧120ft·lb; (ii) has an ARM impact ductility of ≧50%, and; (iii) passes anESCR test Condition B100 and a comparative wall structure fails saidESCR test Condition B100; wherein said wall structure comprising saidethylene interpolymer product comprises said first ethylene interpolymersynthesized using a single-site catalyst formulation, said secondethylene interpolymer synthesized using a first heterogeneous catalystformulation and optionally said third ethylene interpolymer synthesizedusing said first or a second heterogeneous catalyst formulation; whereinsaid comparative wall structure has the same construction but saidethylene interpolymer product is replaced with a comparative ethyleneinterpolymer synthesized using one or more single-site catalystformulations; wherein, said ESCR test Condition B100 is passed if afailure time (F^(B) ₅₀) is ≧1000 hr or said ESCR test Condition B100 isfailed if said failure time (F^(B) ₅₀) is <1000 hr, wherein said failuretime (F^(B) ₅₀) is estimated graphically as described in Annex A1 ofASTM D1693, and; wherein said ARM impact mean failure energy and saidARM impact ductility are measured at −40° C. according to ASTM D5628.42. The rotomolded article of claim 4, wherein said wall structure: (i)has an ARM impact mean failure energy of ≧120 ft·lb; (ii) has an ARMimpact ductility of ≧50%; (iii) passes an ESCR test Condition A100 and acomparative wall structure fails said ESCR test Condition A100, and;(iv) passes an ESCR test Condition B100 and a comparative wall structurefails said ESCR test Condition B100; wherein said wall structurecomprising said ethylene interpolymer product comprises said firstethylene interpolymer synthesized using a single-site catalystformulation, said second ethylene interpolymer synthesized using a firstheterogeneous catalyst formulation and optionally said third ethyleneinterpolymer synthesized using said first heterogeneous catalystformulation or a second heterogeneous catalyst formulation; wherein saidcomparative wall structure has the same construction but said ethyleneinterpolymer product is replaced with a comparative ethyleneinterpolymer synthesized using one or more single-site catalystformulations; wherein, said ESCR test Condition A100 is passed if afailure time (F^(A) ₅₀) is ≧1000 hr or said ESCR test Condition A100 isfailed if said failure time (F^(A) ₅₀) is <1000 hr and said ESCR testCondition B100 is passed if a failure time (F^(B) ₅₀) is ≧1000 hr orsaid ESCR test Condition B100 is failed if said failure time (F^(B) ₅₀)is <1000 hr, wherein said failure times (F^(A) ₅₀) and (F^(B) ₅₀) areestimated graphically as described in Annex A1 of ASTM D1693, and;wherein said ARM impact mean failure energy and said ARM impactductility are measured at −40° C. according to ASTM D5628.